For the existing method to calculate the life scatter factor only fits to complete data

it is not suitable for the time truncated zero-failure data which are significantly increasing in the life tests. Therefore

this study introduced the theory of complete data scatter factor into the situation of time truncated zero-failure data

and proposed a method for the life analysis of normal time truncated zero-failure data by providing the formula of life scatter calculation. According to the theory analysis and calculating result

it shows that the scatter factor of time truncated zero-failure data is significantly smaller than the completed data

and thus the method proposed by this study can fully utilize the depressed safety life by complete data scatter factor method.