Main content

Inference comparing two groups or populations

AP Stats: DAT (BI), DAT‑3 (EU), UNC (BI), UNC‑4 (EU), VAR (BI), VAR‑6 (EU)
AP Stats: DAT (BI), DAT‑3 (EU), DAT‑3.C (LO), DAT‑3.C.1 (EK), DAT‑3.D (LO), DAT‑3.D.1 (EK), DAT‑3.D.2 (EK), UNC (BI), UNC‑4 (EU), UNC‑4.N (LO), UNC‑4.N.1 (EK), VAR (BI), VAR‑6 (EU), VAR‑6.H (LO), VAR‑6.H.1 (EK), VAR‑6.H.2 (EK), VAR‑6.H.3 (EK), VAR‑6.I (LO), VAR‑6.I.1 (EK), VAR‑6.J (LO), VAR‑6.J.1 (EK), VAR‑6.K (LO), VAR‑6.K.1 (EK)
AP Stats: UNC (BI), UNC‑4 (EU), UNC‑4.V (LO), UNC‑4.V.1 (EK), UNC‑4.V.2 (EK), UNC‑4.W (LO), UNC‑4.W.1 (EK), UNC‑4.X (LO), UNC‑4.X.1 (EK), UNC‑4.X.2 (EK), UNC‑4.Y (LO), UNC‑4.Y.1 (EK), UNC‑4.Y.2 (EK)

About this unit

If a poll from one location shows 55% of voters support a measure, but a poll from another location shows 45% support, does that mean there is a difference between the two populations? We can make a confidence interval to estimate the difference, or do a significance test to see if the difference is significant. We'll use similar methods to compare the means of two groups.