The t-test is a statistical test used to determine if there is a significant difference between the means of two groups. It is commonly used to compare the means of a control group with a treatment group or to compare the means of two independent groups.

The formula for the t-test is:

t = (x̄1 – x̄2) / √[(s1^2 / n1) + (s2^2 / n2)]

where:

- x̄1 is the mean of the first group
- x̄2 is the mean of the second group
- s1 is the standard deviation of the first group
- s2 is the standard deviation of the second group
- n1 is the sample size of the first group
- n2 is the sample size of the second group

The resulting t-value can be compared to a critical value from a t-distribution table to determine the level of statistical significance. If the t-value is greater than the critical value, then it can be concluded that there is a significant difference between the means of the two groups.