hypothesis testing and linear regression

What is Null Hypothesis (H0)

The assumption that there is no effect or change

What is alternative hypothesis (H1)

The assumption we are trying to support with evidence

What is Type 1 Error?

Incorrectly rejecting H0 when it is true (false positive)

What is Type II Error?

Failing to reject H0 when it is false (false negative)

What is a confidence interval?

It provides a range of values that likely contains the true population parameter.

What do confidence intervals do?

It is a way of expressing the uncertainty around an estimate from sample data

What do confidence interval help to interpret?

They help contextualise points estimates, adding depth to our understanding by indicating a range rather than a single, fixed value

What is hypothesis testing?

A statistical method for deciding whether sample evidence supports a claim about a population.

Why do we use hypothesis testing?

Because studying an entire population is impractical; we use sample data to infer population patterns.

Why is random sampling important?

It reduces bias, increases generalisability, and improves validity.

What is α (alpha)?

The probability of making a Type I error.

What does α = 0.05 mean?

A 5% risk of incorrectly rejecting H0.

What is a p-value?

The probability of observing the data if H0 is true.

What does a low p-value mean?

Strong evidence against H0.

Does rejecting H0 prove H1 is true?

No; it only indicates sufficient evidence.

Does failing to reject H0 prove H0 is true?

No; it means insufficient evidence.

What is a confidence interval (CI)?

A range of values likely to contain the true population parameter.

Interpretation of a 95% CI?

If repeated many times, 95% of intervals would contain the true value.

Which test should you use to check if a sample mean differs from a known value?

One-sample t-test.

Which test should you use to compare two related measurements (before/after)?

Paired t-test.

Which test should you use to compare two independent groups with normal data?

Independent samples t-test.

Which test should you use to compare two independent groups with non-normal data?

Mann–Whitney U test.

Which test compares the means of 3 or more independent groups?

ANOVA.