家蚕繭調査におけるサンプリングの方法
(II) 繭層重平均値の推定
1965 年 34 巻 1 号 p. 24-31
詳細
1965 年 34 巻 1 号 p. 24-31
In this paper I report sampling experiments for estimating the population mean value of silkworm cocoon layer. The materials were obtained from cocoons of Shi 122×Nichi 122 (1, 000 individuals for each sex). Measurements were carried out using a balance which was properly prepared for weighting cocoon layers, the scale being read by every 0.15cg. The results obtained are as follows:
1. The frequency distributions of the cocoon layer weights are shown in Table 1. It is shown in Table 2 that the distribution types of the cocoon layer weights in the population are not the normal ones.
2. The distribution-types of the sample mean value (in the size of sample n≥10) are shown to be normal ones in Table 4 and Table 5.
3. Various formulae deduced from the normal distribution can be safely applied to the cocoon layer weight values through the central limit theorem, for example the calculated values are almost equal to the observed ones with regard to the standard deviation of the sample mean values.
4. The size of the sample (the number of cocoon layers) can be computed using the formula (4), in the paper I.
