If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

# Unit: Collecting data

AP Stats:
DAT (BI)
,
DAT‑1 (EU)
,
DAT‑2 (EU)
,
VAR (BI)
,
VAR‑1 (EU)
,
VAR‑3 (EU)
Not feeling ready for this? Check out Get ready for AP® Statistics.

#### 0

Possible mastery points

AP Stats:
DAT (BI)
,
DAT‑2 (EU)
,
DAT‑2.A (LO)
,
DAT‑2.A.1 (EK)
,
DAT‑2.A.2 (EK)
,
DAT‑2.A.3 (EK)
,
DAT‑2.A.4 (EK)
,
DAT‑2.B (LO)
,
DAT‑2.B.1 (EK)
,
DAT‑2.B.2 (EK)
,
DAT‑2.E (LO)
,
DAT‑2.E.1 (EK)
,
DAT‑2.E.2 (EK)
,
DAT‑2.E.3 (EK)
,
DAT‑2.E.4 (EK)
,
DAT‑2.E.5 (EK)
,
DAT‑2.E.6 (EK)
,
VAR (BI)
,
VAR‑1 (EU)
,
VAR‑1.E (LO)
,
VAR‑1.E.1 (EK)

## Potential problems with sampling

### Practice

#### Quiz 1

Level up on the above skills and collect up to 320 Mastery points

## Random sampling and data collection

AP Stats:
DAT (BI)
,
DAT‑2 (EU)
,
DAT‑2.C (LO)
,
DAT‑2.C.1 (EK)
,
DAT‑2.C.2 (EK)
,
DAT‑2.C.3 (EK)
,
DAT‑2.C.4 (EK)
,
DAT‑2.C.5 (EK)
,
DAT‑2.D (LO)
,
DAT‑2.D.1 (EK)

### Practice

#### Quiz 2

Level up on the above skills and collect up to 240 Mastery points

AP Stats:
DAT (BI)
,
DAT‑2 (EU)
,
DAT‑2.B (LO)
,
DAT‑2.B.3 (EK)
,
VAR (BI)
,
VAR‑3 (EU)
,
VAR‑3.A (LO)
,
VAR‑3.A.1 (EK)
,
VAR‑3.A.2 (EK)
,
VAR‑3.A.3 (EK)
,
VAR‑3.A.4 (EK)
,
VAR‑3.B (LO)
,
VAR‑3.B.1 (EK)
,
VAR‑3.C (LO)
,
VAR‑3.C.1 (EK)
,
VAR‑3.C.2 (EK)
,
VAR‑3.C.3 (EK)
,
VAR‑3.C.4 (EK)
,
VAR‑3.C.5 (EK)
,
VAR‑3.C.6 (EK)
,
VAR‑3.C.7 (EK)
,
VAR‑3.C.8 (EK)
,
VAR‑3.C.9 (EK)
,
VAR‑3.E (LO)
,
VAR‑3.E.1 (EK)
,
VAR‑3.E.2 (EK)
,
VAR‑3.E.3 (EK)
,
VAR‑3.E.4 (EK)

## Inference and experiments

### Practice

#### Quiz 3

Level up on the above skills and collect up to 320 Mastery points
Up next for you:

#### Unit test

Level up on all the skills in this unit and collect up to 1100 Mastery points!