2025 Volume 4 Issue 2 Pages 469-484
With increasing frequency, we see the intersection of rigorous qualitative methodologies in mixed methods studies. While we find grounded theory, ethnography, narrative, and phenomenology studies representing the qualitative strand in mixed methods projects, a new approach from Japan, the Trajectory Equifinality Approach (TEA), holds promise as an intersecting qualitative methodology for examining behavior change and decision-making over time. Unfortunately, this approach has limited discussion in the English-speaking literature to date. In this article, we advance the emerging "intersected" mixed methods design, describe using qualitative methodologies as the intersected "strand" in a mixed methods study, advance TEA as a rigorous methodology in a mixed method design, and present an empirical mixed methods study using TEA in terms of its worldview, questions, data collection, data analysis, validity, and writing structure. This article contributes to the mixed methods literature by advancing a behaviorally oriented, longitudinal qualitative approach (TEA), encouraging its use in mixed methods research, and expanding the discussion of "intersected" mixed methods designs.
Mixed methods designs have evolved over the last 20 years (Creswell & Plano Clark, 2023). Mixed methods research involves a study in which the researchers collect quantitative and qualitative data, combine or integrate them, and then draw metainferences or insight from the integration (Creswell & Plano Clark, in press). Today's mixed methods literature indicates several issues occupying the attention of scholars who write about the methodology. One emerging issue is the intersection of rigorous qualitative methodologies with mixed methods research. Recently this type of design has begun to appear in the mixed methods literature. By intersection, we mean blending a qualitative methodology (e.g., grounded theory, case study, and others) with mixed methods research. A "methodology" is the "overall approach to research linked to paradigm or theoretical framework, while the method refers to systematic modes, procedures, or tools used for collecting and analyzing data" (Mackenzie & Knipe, 2006, p. 197). Methodology represents a broader, more encompassing view of the research process while methods apply to the data collection, analysis, and interpretation phases of the research process. As new qualitative methodologies combined with mixed methods research, we need to understand how and in what way the intersection occurs.
This paper highlights and illustrates the intersection of a qualitative methodology - the Trajectory Equifinality Approach (TEA) - with mixed methods research. TEA is a qualitative approach for describing the diversity of human life. This approach is longitudinal research that focuses on the change process over time, particularly in behavioral change and decision-making. We begin this article by tracing the evolution of mixed methods research designs. This evolution started with "core designs," moved into complex or "hybrid" designs, and then formed into "intersected" designs involving the combination of qualitative methodologies and mixed methods research. Following this discussion, we review the characteristics of a few select qualitative methodologies and discuss the major tenets of TEA. Finally, to discuss how the methodology of TEA intersects with mixed methods design, we share an empirical study from Japan illustrating components of TEA's methodology and how it intersected within a rigorous intervention design.
Evolution of Mixed Methods Designs and Recent Intersected DesignsMixed methods research designs have been extensively discussed in the literature (Creswell & Plano Clark, 2023). We begin with "core designs," introduced and widely discussed in the mixed methods literature today. These designs combine quantitative and qualitative data in various procedures, such as the convergent designs, the explanatory sequential designs, and the exploratory sequential designs (Creswell & Plano Clark, 2018). As early as 2007, Creswell and Plano Clark began introducing the concept of "complex" designs in which the "core designs" embed within larger frameworks or processes (e.g., in experiments, in evaluation projects). This advanced design thinking viewed mixed methods research as more than a "stand-alone" design and showed that mixed methods research can effectively link with frameworks external to the specific mixed methods study. The next step in the evolution came when Plano Clark and Ivankova (2016) discussed the types of frameworks for embedding the "core" designs. They commented that "core" mixed methods designs might embed within other designs (e.g., experiments), theories (e.g., feminist theories), and methodologies (e.g., case studies). Then the issue arose as to what to call these embedded designs, and the names varied from "advanced designs" (Plano Clark & Ivankova, 2016), "complex designs" (Creswell & Plano Clark, 2018), and "hybrid" design, a label we currently use and recommend (Plano Clark & Creswell, in press).
Of special interest to us among the types of hybrid designs was the design of embedding mixed methods research into methodologies, especially qualitative methodologies. We have seen in the recent literature an increased focus on embedding mixed methods research into qualitative methodologies. For example, Waller et al. (2021) combined narrative research with mixed methods, Martiny et al. (2021) linked phenomenology research into mixed methods, and Kawamura et al. (2009) and Guetterman et al. (2019) combined grounded theory and mixed methods. Linking qualitative methodologies into mixed methods research encouraged us to consider TEA as a rigorous qualitative methodology to intersect. Then the issue arose as to what to call this type of mixed method research design. Exploring discussions in recent literature, we found authors using terms such as "inter-method mixing" (Creamer & Schoonenboom, 2018), "creative intermingling" (Creamer, 2018), a "blended approach" (Guetterman et al., 2019), and "inter-methodology mixing" (Cameron, 2024). We felt most comfortable using"intersecting designs," a term mentioned by several authors in recent publications (Dejonckherre et al, 2019; Ivankova & Wingo, 2022; and Plano Clark & Ivankova, 2016). Thus, in this article we discuss "intersecting" TEA within mixed methods research. We could also say that an "intersected design" is one in which a methodology (mixed methods) is intersected with a methodology (TEA) (see Cameron, 2024).
The intersected mixed methods design is not to be confused with a "dominant" or "qualitatively driven" mixed methods design. Such a "qualitatively driven" design, as advanced by Morse (2010), Hesse-Biber (2015), and Poth and Shannon-Baker, (2022) privileges a qualitative approach (in terms of epistemology and methodology) as the core of the overall mixed methods project. The quantitative approach takes a secondary role in the mixed methods design. In our "intersected" design in this paper, neither the qualitative or quantitative methodology takes precedence or is privileged over the other. "Qualitatively driven" introduces a power dynamic into mixed methods research, a methodology that we believe does not honors the equal status of quantitative and qualitative research. Later in this paper we will discuss using the TEA methodology in a mixed methods quantitative intervention design where both TEA and the intervention hold equal status.
Qualitative MethodologiesNow we turn to a more detailed discussion about qualitative methodologies. Indeed, the qualitative strand may take the form of qualitative data as in "core" designs. However, it may also represent more than simply the methods (e.g., data collection, analysis, and interpretation), it may reflect the entire research process from initial philosophical assumptions (or worldviews or paradigms) to the interpretations of findings. Mayan (2023) adequately summarizes the meaning of "methodology" in qualitative research:
Methodology flows from the foundations of qualitative inquiry which includes paradigms, ontology, epistemology, and theoretical orientation... methodology provides the much- needed direction and justification for the actual methods ... including sampling, data collection strategies, analysis techniques, and the production and presentation of findings. (p.45)
We realize that the term, "qualitative methodology" often goes by different names in the literature and is used interchangeably with other terms, such as "qualitative approach" or "qualitative design" (Creswell & Poth, 2024), "qualitative inquiry" (Denzin & Lincoln, 2023), and "qualitative approaches to inquiry" (Levitt et al., 2018). Mayan (2023) reviewed 18 possible qualitative methodologies in her chapter. In our discussion, we will refer to the five types of qualitative methodologies presented in the recent edition of the Creswell and Poth (2024) book, realizing that the five mentioned by them are popular but not exhaustive of the possibilities.
Creswell and Poth (2024) presented five "qualitative approaches" (or methodologies) in their book: narrative research, phenomenology, grounded theory, ethnography, and case studies. The authors advanced the five approaches as methodologies with each chapter beginning with philosophical assumptions, moving on to purpose statements and research questions, data collection strategies, data analysis approaches, interpreting the data, and writing structures and evaluation criteria. Each of the five approaches was described for distinct steps in the research process (e.g., research questions, data collection, data analysis). Key literature references helped support the discussion, and examples of each approach were in the appendix to the book. The book came along in the 1990s (in the first edition) when authors were advancing different types of qualitative studies and books on the approaches or methodologies (e.g., Strauss & Corbin, 1990; Moustakas, 1994; Stake, 1995). The five approaches presented in the Creswell and Poth (2024) book are also summarized as a final chapter in the Creswell and Bãez (2020) qualitative book on 30 essential qualitative skills.
To distinguish among different qualitative methodologies, researchers can focus on the "outcomes" or the result of completing one of the qualitative approaches (Creswell & Poth, 2024). A narrative research study reports stories of individuals (usually one or two) told in their voice or the collective voice of the participants and the author. A phenomenology reports on common experiences called the "essence," of a small group of individuals who have all experienced the same phenomenon. This "essence" takes the form of description at the end of a study incorporating two ideas: what the individuals have experienced and how (context) they experienced it. An ethnography reports on a defined cultural group and how this group, over time, has acted, communicated, or talked as a group. The reader gains an in-depth understanding of a cultural group that may not be familiar and learns how the group "works." A grounded theory study results in a theoretical model, described in the study or presented as a visual model that captures the process or action about how an event, activity, or organization evolves. A case study results in in-depth case profiles (e.g., organization, school, individuals). This profile typically includes a description of the case and themes within and across the cases.
The organization of the Creswell and Poth (2024) book into topics such as worldview, research questions, data collection and analysis, validity, and writing structure provides a helpful approach to discuss a methodology useful in a mixed methods study, such as the Japanese Trajectory Equifinality Approach (TEA).
The Trajectory Equifinality Approach (TEA)We propose TEA as a qualitative methodology to be intersected with mixed methods research. It reflects a Japanese cultural orientation to qualitative research, and it presents a behavioral model for inquiry. We introduce the Trajectory Equifinality Approach (TEA) which captures participants' longitudinal behavior changes and decision-making processes over time. This approach holds great promise of advancing a methodology primarily developed in Japan for qualitative research, relating nicely with the qualitative "strand" in mixed methods research, and introducing a methodology well-suited longitudinally for participant changes over time. We advance a description of TEA and then end by analyzing a Japanese empirical mixed method study using TEA for its methodological components like the Creswell and Poth (2024) book: worldview, questions, data collection, data analysis, validity, and writing structure.
TEA is a qualitative methodology in cultural psychology developed over the last twenty years. It primarily uses qualitative interviews to capture and describe the process of change in life (e.g., behavior change, decision-making change). It focuses on the longitudinal changes for a small number of individuals (e.g., their life stories and how their behavior changes over time), and the researcher graphs the behavioral changes in individual trajectories. It comes out of cultural, developmental, and behavioral psychology, and equifinality means individuals in a study reach the same state from different initial conditions and in different ways over time, an idea emanating from the work of Bertalanffy (Sato et al., 2006). Trajectory refers to each unique individual's different pathway to reach a final behavioral change point. For example, all people are born, grow up, have various experiences, and die. Although they reach the same endpoint of death, none of their life trajectories are the same. Similarly, TEA captures the diversity of people's life course trajectories over time. As a qualitative methodology, TEA stands as a qualitative methodology alongside others, such as grounded theory, ethnography, and case studies.
The basic components of TEA. Understanding TEA requires learning about three interconnected basic components, as shown in Figure 1: Historically Structured Inviting (HIS), Trajectory Equifinality Modeling (TEM), and Three Layers Model of Genesis (TLMG). First, HSI is recruiting and inviting participants who have experienced the phenomenon the researcher explores in the study (e.g., behavioral change). Second, TEM (Trajectory Equifinality Modeling) presents a visual model (or figure) of the participant's experience over time. In this model, reading from the left to the right (or possibly up to down), the researcher graphs trajectories for each individual or the collectivity of individuals over time to show their changes. TEM is a framework for depicting in a linear way human behavior, making choices, and changes over time (Sato et al., 2006). This change of state occurs with the passage of time and background context (Yasuda, 2015). Within the trajectories of individuals, the researcher identifies various points (see Table 1 for key terms of conceptual tools in TEM). Thus, a researcher needs to learn the central elements (or conceptual tools) and their definitions to use TEA. These popular tools often include the endpoint that answers the research question, the equifinality point (EFP), the bifurcation point where an individual’s change may go in one of two directions (BFP), social direction are social and cultural factors that inhibit toward EFP, SD, and social guidance that promote toward EFP, SG.
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The researcher might also consider the possibility of an individual's behavior moving in the opposite direction to fulfill the EFP - a polarized equifinality point (P-EFP). In the trajectory, individuals also may experience a common phase or event, called OPP (obligatory point). Finally, along with these trajectories, the researcher draws a single line below the diagram to show that time changes in one direction, the movement toward the outcome in one direction over time, called by TEA researchers as "irreversible time." In sum, a complex diagram with longitudinal trajectories are drawn for the reader, indicating many components of behavior change for individuals under study.
Third, TLMG (Three Layers Model of Genesis) represents the phase of TEA where researchers seek to understand the transformation process of individual behavior change in more detail. The researchers’ foci are understanding participants' behavior on the BFP (bifurcation point when behavior can go in two different directions). In TLMG, the researcher understands the participant using three layers leading to the BFP: the transformation and stability of behavior/choices (first layer), the signs of change to occur (second layer), and finally the development or establishment of stable participant beliefs/values (third layer) (Yasuda, 2015). People's direct, lively experiences first occur in the first layer in an endless sequence of irreversible time (Valsiner, 2007). Individuals experience various actions, feelings, and thoughts. The second layer is the 'sign' level. This level is where signs occur, and they can take various forms, such as pictures, sounds, and voices. Whether they can become signs depends on the meaning given by the people (participants) who receive them. Some events or experiences can be value-transforming signs for a person. The third layer is the level of value/belief transformation. This level represents the transformations individuals make as they approach BFP. These three components - HSI, TEM, and TLMG - form an indispensable trilogy for understanding the life path of an individual or individuals in irreversible time (Sato, 2016).
Origin and history of TEA. TEA, launched by Valsiner, Sato, and their colleagues, has been used in Japan for 20 years in various research fields, including psychology, nursing, education, childcare, and business. TEA developed from the original idea of Valsiner, an Estonian American cultural psychologist, who examined the phenomenon of multiple trajectories and equifinality in human development. Its origins come from an important encounter in 2004 between pioneer Valsiner and the Japanese psychologist Sato (Sato, et al., 2021). In Sato's research presentation of a research study about pocket money at a 2004 symposium, he created the first TEM diagram. It is the first TEM diagram in Sato's presentation that led to a breakthrough in the semiotic cultural psychology of Valsiner. Afterward, at Valsiner's request, Sato spoke at a symposium at the International Congress of Psychology (ICP) in Beijing, China in 2004. Sato presented this topic at the symposium: 'The end of methodological colonialism in psychology: from samples to systematic studies of individuals." With Yasuda and Kido, graduate students at the time, Sato worked on elaborating TEM as a research method in preparation for his speech. He recalled later that his speech became the basis and major foundation for the development of TEA and its key components (Sato, 2015, 2016; Sato et al.2021). In the development of TEA, Sato has argued that methodology should be a shared resource (Sato, 2012) and was opposed to the establishment of pre-conditions on its use, such as the existence of a 'master' teacher as an authority on TEM, or the requirement to attend a course to use it. The TEM research association (now the TEA Research Association) in Japan was established with the participation of researchers interested in TEA and the theory's proponents, Sato and Yasuda. Active discussions began to take place. This research association has uniquely been an open system where researchers from diverse fields gather, contribute, and accept the theoretical development of TEA and its elaboration. Sato and colleagues innovated in many of the concepts used in TEA trajectories, such as BFP, SD, SG, OPP and others.
Conducting TEA methodology. The procedure for conducting a TEA methodology in mixed methods research has been reported in another publication (Hirose & Creswell, 2022). It involves a researcher deciding if the research problem merits examining behavioral or decision-making change over time, defining the final EFP as the research question, and inviting individuals to address the question. Next, the researcher conducts qualitative interviews with these individuals (a small number), analyses data and creates and graphs trajectories for them. Validity of the results in TEA can be based on triangulation of the data, multiple interviews for saturation, and expert reviews of the study. The trajectories then become the qualitative data "strand" in the mixed methods study. In a mixed methods convergent design, the trajectory results can merge with quantitative data from participants, be represented in a joint display, and provide insights to address the overall problem in the study. As another example, in an exploratory sequential mixed methods design, the trajectory information can point toward a survey for collecting information or help to design an intervention or an experiment. Also, the trajectories could be intersected in an intervention study as a qualitative phase to inform an experiment as illustrated in the following TEA empirical study.
An Illustration of a TEA Empirical Study in Mixed Methods ResearchWe will illustrate a mixed methods study employing TEA with the Hirose (2018) research and its use of TEA (see Hirose & Creswell, 2022). First, we will discuss the Hirose (2018) study to provide the context for understanding our illustrated project. Then, we will discuss TEA as a methodology, covering the components of the research process, including worldview, research questions, data collection, data analysis, validity, and the writing structure.
The Hirose (2018) study. Using TEA as the qualitative "strand" to conduct a mixed method study, the researcher identifies individuals who can provide insight into a problem, gathers interview data from them, analyze data, then develops trajectories on a graph of each individual and forms conclusions about the meaning of graphs of multiple individuals and their behavioral changes over time. Researchers can set this process within a mixed methods study, and we illustrate it using the evaluation research of a behavioral support program for mothers of adolescent with autism spectrum disorder (ASD) in Japan by Hirose (2018).
The Hirose study (2018) aimed to evaluate and improve a community-based developmental support program for families of adolescents with ASD in Japan. The family-centered program focused on (1) understanding characteristics of ASD at the adolescent stage of age 18 years old and older and 2) providing behavioral training for families to improve good communication between the parents and children at home. This study also addressed a pressing problem in Japan - called the "Hikikomori" problem of adolescent social withdrawal (Suwa et.al., 2003). The program consisted of four training sessions for the families (psychoeducational intervention training; positive behavior support and affirmations; applied behavioral analysis for understanding the adolescents’ behavior; and approaches for addressing the children’s problems). A follow-up session occurred six months after the program concluded. The program was mainly attended by mothers who had only realized their children had ASD characteristics when the children became adolescents. The mother had never participated in a support program like this one which was held over multiple sessions.
The research approach represented a qualitative methodology with a participatory worldview involving collaboration among Kwansei Gakuin University, Kobe City, and the four branches of ASD support centers in Kobe, Japan. It also involved a mixed methods research design with multiple phases for evaluating the program, embedded exploratory and explanatory sequential core designs (see Figure 2) in the phases based on data gathered from 2013-2018, and intersected TEA as a Phase 3 qualitative methodology in the mixed methods intervention design.
As shown in Figure 2, the framework consisted of an initial qualitative needs assessment phase prior to training with 58 participants (mothers and fathers) who had adolescents with ASD (Phase 1), followed by a preliminary single-case quasi-experimental quantitative design with 44 participants (mothers and fathers) (Phase 2), a qualitative follow-up with 6 mothers (Phase 3) using TEA as the qualitative approach, and ending with a final small group comparison experiment with 8 mothers (Phase 4).
For quantitative data, several indicators (e.g. GHQ12, PANAS, Family Involved Behavior Questionnaire, Social Validity) were gathered before, during, and after the program intervention and measured using a questionnaire. Hirose conducted qualitative interviews with 6 mothers for the qualitative "strand" in Phase 3. As a qualitative methodology of analysis, TEM was employed for the mothers' trajectories to consult with the ASD support center, and TLMG for the details of the process of behavioral change of the mothers resulting from their participation in the program.
We now discuss the Hirose community-based program evaluation study by first stating common elements in the process of qualitative research and then suggesting how the Hirose study reflected the elements. In this way, the evaluation study included a strong qualitative methodology intersected within a mixed methods study.
Worldview in the illustrated empirical study. Worldviews represent the underlying philosophical assumptions, beliefs, and values researchers bring to a study (Creswell & Poth, 2024). These assumptions result from the background and culture of the researcher, membership in academic communities, and from reading philosophical assumptions from the literature. An important source for worldview (called "paradigms") are philosophical discussions in the SAGE Handbook of Qualitative Research. In the latest edition (Denzin et al., 2023), the authors mention eight paradigm assumptions shaping how researchers approach their study: positivism, post positivism, constructivism, critical theory, feminism, poststructuralism and postmodern, participatory and emancipatory, and indigenous.
We reflected on the worldviews or paradigm brought by Hirose in her study, recognizing that worldview is seldom discussed in Japanese research. However, in the Hirose study the researcher brought a participatory perspective to the work through collaboration of Kwansei Gakuin University, the City of Kobe, and the four branches of the ASD support center in Kobe, Japan. Further, the interviews with mothers in the program emphasized understanding their meaning of moving toward consultation with the support center - a constructivist approach. Moreover, cultural psychology and semiotics shaped the approach taken by Hirose in her study. Cultural psychology, derived from Vygotsky (Valsiner, 2007), emphasizes the worldview of researchers looking for signs (or semiotics) for their function of mediating between the individual and the object. Semiotics is the study of signs and symbols, what they mean, and their use. Valsiner (2007) also highlighted the need to view participants' signs over time, and that the sign was a signifier of the individual. In examining the behavior change of mothers in the project, Hirose looked for signs of change using TLMG.
Research questions in the illustrated TEA study. Research questions in qualitative research reflect open-ended statements allowing the participants to share multiple perspectives on a problem (Creswell & Guetterman, 2024). Often these questions take the form of a broad central question and several sub-questions (Creswell & Creswell, 2022).
In TEA, the central question typically is stated as: "What are the trajectories over time for individual change leading to EFP?" Researchers' conceptions of EFP vary from project to project depending on their research question. In the Hirose (2018) study, she set two EFPs: "Consult with the ASD Support Center." (EFP 1) and "Mothers realized an improved relationship with their children" (EFP2). Overall, the research question was: "What was the process of behavior change of the mothers leading to the EFP? And the three sub-questions (asked in the interviews) were: "Why did the mothers feel their relationship with their children had improved?" "Why did the mothers change their behavior at home?" "How did the mothers come to consult with the ASD support center (by attending the program)?" These sub-questions focus on addressing the home, the children, and the changing the behavior of families in their homes.
Data collection in illustrated TEA study. The data collection in qualitative research involves a series of activities from recruitment and sampling to collecting different types of data (Creswell & Poth, 2024). In most TEA studies, data collection involves mainly interviews, but other forms of data may also be included, such as video observations or medical record documents. The sampling in the Hirose (2018) study utilized a purposeful sampling strategy of including individuals who could respond to the research questions and attend the program sessions. The TEA Historically Structured Inviting (HIS) was used for inviting the research participants. In TEA, researchers need to respect and invite participants into the study not as a sample, but as important individuals who have experienced a particular event, such as the researcher’s focus on the EFP. During interviews Hirose asked participants about their trajectory to EFP and set the opposite possibility P-EFP. After recruiting participants, the number of study participants was small. In the Hirose (2018) study, she collected verbatim data from multiple interviews with six program participants (all mothers).
Data analysis in the illustrated TEA study. Data analysis in qualitative research involves analyzing the various sources of data, drawing codes and themes, and then creating storylines interrelating the themes (Creswell & Bãez, 2020). In TEA, the data analysis proceeds differently. It involves using two TEA components - TEM and TLMG - although some studies use TEM or TLMG alone. Data analysis in TEA involves proceeding in two directions: a bottom-up process, and a top-down process of analysis. Bottom-up analytical process is an inductive process of basic qualitative analysis procedure where the researcher reads the collected data in detail and inductively codes the data. In the top-down process, the researcher looks at the whole data and analyzes the data based on the tools of TEM (see Table 1).
In the Hirose project, the top-down process proceeded in four steps. First, she set the EFP based on the research question, and then she collected textual data to determine the EFPs and the opposite possibility to EFP (Polarized EFP, P-EFP). Second, Hirose visualized the trajectories. She drew trajectories for each of the six mothers leading to the EFP. Third, Hirose set the BFP and the OPP. She recognized that behavioral choices and values shifted along the trajectory and set the OPP as the mothers' common experiences. Fourth, she identified the factors influencing the BFP. As Valsiner (2015) said that no TEM is complete without analyzing tensions at the bifurcation point (BFP) where a certain behavior is selected. These forces were the cultural, social, and individual factors of social direction (SD) which inhibits the individual from moving toward the equifinality point (EFP) and social guidance (SG), which facilitated moving toward the EFP.
It became clear that the concept of a developmental disorder did not exist when their children were young, and that families made various efforts to deal with their children's difficulties without an understanding of the characteristics of ASD. When individuals came to the ASD support center for advice, some of them did not have sufficient knowledge about developmental disorders and were in a conflicted state. The review of various force factors in the study revealed a social context, such as the lack of a concept of developmental disability, or a family cultural context involving a reluctance of some participants to send their children to see a psychiatrist. Thus, individuals in the program needed specific personal support.
In the Hirose (2018) study, she sought to understand behavior change processes during the program by using TLMG (see Figure 4). The figure is a joint display that includes the TLMG qualitative findings and themes, the quantitative results, and the metainferences. For the TLMG results, she set "interacting with children in daily life" as the first layer, "behavior change with program participation" as the second layer, and "changing behavior improved the relationship with their children" as the third layer. Six participants stated that what contributed to the improvement of their relationship with their children was that they had changed their own behavior to their children. As for the SGs, all the participants mentioned "participation in the program and learning," which included "deepening understanding of developmental disabilities," "acquiring a behavioral perspective" and "practicing homework tasks." By capturing their behavior change process in detail using TLMG, it was shown that program participation and learning contributed to improved relationships with children. In addition, participants needed a safe and secure place for talking about their own stories of behavioral change, and for improving relationships with their children. These findings showed the importance of multi-program sessions for individuals to report and tell their stories.
Validity in illustrated TEA study. Validity has long been a contested topic in qualitative research, and perspectives range from dismissing its importance to rigorous procedures (Creswell & Poth, 2024). One conceptualization involves identifying specific strategies for assessing validity, such as triangulating data among participants and conducting member checks (Creswell & Miller, 2000).
Hirose used two procedures to assess the validity of the research: triangulation and expert review. Triangulation consisted of getting qualitative information from supporters from the four branches of ASD centers and comparing their information with the questionnaire data. Expert review consisted of sharing the results and interpretation with the TEA Association members and gaining their advice about study findings.
The writing structure of the illustrated TEA study. The writing structure for a qualitative study varies considerably depending on the qualitative methodology used. It is important to follow quality criteria when conducting research and employ them in the writing structure of a study (Hirose & Creswell, 2023). In the Hirose TEA study, she followed five quality criteria for writing a TEA study: she (1) created a rationale for using TEA; (2) identified two EFPs that focus on the research questions; (3) analyzed the data from a deductive and inductive perspective, using the conceptual tools of TEM; (4) created a TEM and the TLMG diagrams; (5) and discussed the value and significance of using TEA in the research (Hirose & Creswell, 2024).
How TEA Intersects with the Mixed Methods Intervention DesignReturning to Figure 2 of the overall mixed methods design, TEA formed the major qualitative component of Phase 3, and the results informed the Phase 4 experimental and control group design. The trajectories resulting from Phase 3 TEA indicated the mother's need for personal support in addressing the needs of their children. Also, Hirose learned from the trajectories that the mothers needed the program's public support (from the local government) to motivate them to address their children's needs. In addition, from Phase 3, Hirose learned that the program needed to be modified to provide sustainable support for encouraging the mothers.
Following a mixed methods research approach, the TEA results of Phase 3 were intersected with the Phase 4 design of the intervention. Specifically, the intervention consisted of two groups (recall the Phase 2 experiment had only one group). The groups in Phase 4 were an experimental group and a wait-list (control) group (with small samples). This two-group approach permitted a test of whether the program worked. In this Phase 4 group experiment, the same measures used in Phase 2 were administered. However, in the intervention in Phase 4, Hirose emphasized in the interpretation of Phase 3 family values as an overriding framework for delivering the program. This family values orientation resulted from the TEA trajectories in Phase 3. In addition, through TLMG the program sessions showed the mothers' realization of the need to change their own behavior. There is a saying in Japanese culture that "Oya ga kawareba, kodomo ga kawaru" ("If you change your behavior, the children’s behavior will change"), but this saying has caused pain for many families. Rather than being forced to change their behavior by this saying, the families could change their behavior through this program and find support on their own. In summary, the interpretation from Phase 3 to Phase 4 illustrates the drawing of metainferences informing the intervention.
This paper discussed the Trajectory Equifinality Approach (TEA) as a valuable qualitative methodology useful for the intersection in a mixed methods study. TEA captures participants' behavior change and decision-making processes over time, thus encouraging a longitudinal approach in mixed methods research well-suited for understanding behavioral changes in participants. To use TEA, researchers need to understand the conceptual tools (or terms) used in TEA, become familiar with graphing trajectories, and understand the levels of behavioral change that may occur. TEA, developed primarily in Japan, originated in cultural psychology and contains detailed terms and procedures. Most significant in TEA is its adaption of data analysis to incorporate the drawing of individual trajectories (TEM) and its focus on stages of behavioral change (TLMG).
Further cultural components involve understanding the social context, cultural background, and family culture of the individual's transformation. In Hirose's four-stage design diagram (Figure 2), TEM involved qualitative data collection following the first intervention trial. It then became useful information to inform the final two-group experiment. Thus, TEA became a critical "strand" to explore the trajectories of the mothers' movement toward behavioral change to help identify key concepts explored in the final experiment in her study (phase 3 to phase 4). However, TEA, as employed in the illustrated study, could relate to phase 2 as well as phase 4, but our focus on an intersected design will relate to the intersection between phase 3 and phase 4.
Further, this discussion expands the types of mixed methods designs, the "intersected mixed methods design" that uses TEA as a qualitative methodology with mixed methods research. Thus, we add to the list of qualitative methodologies envisioned by the "hybid" types suggested by Plano Clark and Ivankova (2016). In this way, we extend the discussion about mixed methods designs beyond the "core" and adds to the "hybrid" designs. Further, we see the "intersected" design as useful in mixed methods studies. Its use within Hirose's four-stage model provided rigor in her qualitative phase and insight into the trajectories of change for the mothers, contributing to new features being added into her final intervention design.
This discussion presents only one qualitative methodology or "strand" useful in mixed methods research. Others have been documented in the mixed methods literature (e.g., narrative research and mixed methods), and additional ones will emerge in the future. We recognize that the detailed nature of TEA may discourage researchers from understanding and using it. However, our discussion of procedures should provide an introductory understanding of TEA to encourage researchers to consider its use, read about it, and apply it to their studies. In this way, TEA becomes a viable strategy for intersecting the qualitative "strand" in a mixed methods study. Further, it adds a longitudinal component into mixed methods research, a component seldom included in a mixed methods study (see Plano Clark, et al., 2015). Thus, this article contributes to the mixed methods literature by advancing a behaviorally oriented, longitudinal qualitative approach (TEA), encouraging its use in mixed methods research, making it accessible to an international audience, and expanding on the mixed methods literature by contributing an "intersected" design linking a qualitative methodology to mixed methods research.
