Hypothesis Testing & the Null Hypothesis

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Null (H0 = no difference/no effect) vs alternative (H1). We test whether data are consistent with H0. One- vs two-tailed. Logic of 'reject/fail to reject' the null — we never 'prove' H1. Significance level α (conventionally 0.05) set in advance. Leads into p-values. Exam tip: a non-significant result ≠ proof of no effect (absence of evidence ≠ evidence of absence).

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