The normal population characteristics

such as the mean

standard deviation

percentile

percentage and coefficient of variation

are often tested in engineering. Based on the theory of confidence tests

the test methods for normal population characteristics are presented in this paper

which include the strong test

the weak test and the weak-strong test. Compared with the hypothesis tests and sampling inspections for normal distribution

the confidence tests can overcome the disadvantage that to accept a null hypothesis may simply mean that it is not rejected by significance hypothesis tests

and greatly improve the test precision. The confidence tests can also bring more convenience in engineering

as that the tests for the percentile and percentage of normal population that are difficult in hypothesis tests can be easily solved by the present method.