1, a population mean is known;

2. Sample mean and standard deviation can be obtained;

3. The sample comes from a normal or nearly normal population.

T-test is mainly used for small sample size (such as n

Extended data:

The selected test method must meet its applicable conditions (note: the premise of t test: from the normal distribution population; Random sample; When comparing the mean, it is required that the population variance of the two samples are equal, that is, they have homogeneity of variance). Theoretically, even if the sample size is very small, t-test can be carried out. (If the sample size is 10, some scholars say even a smaller sample will do), as long as the variables in each group are normally distributed, there will be no significant difference in variance between the two groups.

As mentioned above, the normality hypothesis of data can be estimated by observing the distribution of data or conducting normality test. The hypothesis of homogeneity of variance can be tested by F test or Levene test. If these conditions are not met, the modified t test or nonparametric test can be used to compare the mean values of the two groups.

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