When we are doing Hypothesis testing with t-test, we aim to determine if there is a statistically significant difference between the means of two populations or between the means of the same population measured at different times. The question we’re asking is: “Is the observed difference in sample means likely due to random chance, or does it reflect a true difference in population means?”
- The Null Hypothesis is: “The two groups have the same mean”.
- The Alternate Hypothesis is: “The two groups have different means”.
If the null hypothesis is true, what’s the probability that, taken a sample from the population, there is actually a difference in the value? If this value (called the p-value) is very improbable (with a predefined threshold, such as 5%) then the null hypothesis is incorrect, since, even if small, there is a difference.
statistics resources: T-test, ANOVA and Chi Squared test made easy. - YouTube