Then, give test and measure knowledge. Take means of both groups. Suppose there is a difference. Hopefully, the experimental group will get higher mean. Samples must be random from respective populations.
Observations are independent of one another.
No one in the experimental group can also be in the control group. Population distributions are normal 4. If assumptions are violated, the probability levels we use are not the ones we select. But, if samples are large, t test may be conducted with confidence that results are true probability values even though not normally distributed. Depends on how non-normal.