🧪 Testing Ideas

This is the heart of research: how do we know an effect is real and not just luck? Block 3 builds the answer from the ground up — first probability and the bell-shaped sampling world of the central limit theorem, then the logic of hypothesis testing (null vs. alternative, p-values, the two kinds of error), and finally the t-test family: one group vs. a number, two separate groups, and the same group measured twice.

By the end of Block 3 you can…

✓State a null and an alternative hypothesis for a research question.
✓Read a p-value against alpha (usually .05) and decide whether a result is significant.
✓Explain the difference between a Type I and a Type II error.
✓Run a one-sample, an independent-samples, and a paired-samples t-test.
✓Pick the right t-test for a study just by looking at how the data were collected.

Test yourself

Block 3 Practice Test

12 multiple-choice questions spanning Units 8–12 — probability and the CLT, the logic of hypothesis testing, and the three t-tests — with a few light calculations, just like the real thing. Practice only; never graded.

Sigma says: For the whole t-test family, the first move is always the same — read the design before you read the numbers. One group vs. a number, two separate groups, or the same group twice? Name that, and the right test names itself.