Abstract
In this present report, the method to determine sterilization effect by means of counting the number of colonies has been mathematico-statistically analyzed.
This method is generally accepted to result in a wide dispersion of measured effects.
The error factors of this method are discussed by using the variance or standard deviation and relations between these, factors are expressed by using a few equations.
It is found that the dispersion of the estimated value of sterilization effect; mortality, can be expressed as shown in eqntions 11, 12.
Thus, the dispersion of the number of colonies cultured in each petri dish (σXij) and the dispersion of the estimated value of the number of survived spores in their suspensions (σXi) are obtained experimentally. And these dispersions can be expressed as shown in (2) - (5) and (6) (7).
When using improved method proposed herein, the dispersions of sampling errors will equal to those of measuring errors.
It is concluded from the above presentation that the dispersion of mortality measured by means of using the improved method is much smaller than that measured by the conventiOnal method.
