Two Sample T-test
Two Sample T-test Introduction A two sample t hypothesis tests also known as independent t-test is used to analyze the difference between two unknown population means. The Two-sample T-test is used when the two small samples (n< 30) are taken from two different populations and compared. Assumption The data are continuous The data are normally distributed in each group. The sample is a simple random sample form its population. Each individual in the population has an equal probability of being selected in the sample. The variances for the groups are equal. Hypotheses The null hypothesis ( H 0) and alternative hypothesis ( H 1) of the one sample T test can be expressed as: H0: µ1 = µ2 H1: µ1 ≠ µ2 where µi is the population mean of population i . Test Statistic Where n1 and n2 are sample sizes x̅1 and x̅2 are means of sample sizes Sp is the pooled standard deviation P-value P-value = Pr(|t_n1+n2-2| > |t|) = 2Pr(t_n1+...
