AP Statistics · Topic 8.3

Carrying Out a Chi-Square Test for Goodness of Fit Practice

Part of Inference for Categorical Data: Chi-Square.(VAR-8.B)

Practice questions

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Sample questions

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  1. Sample 1difficulty 2/5

    A chi-square goodness-of-fit on a six-category variable returns chi-square = 11.2 and p = 0.048.

    GOF Output chi-square = 11.2 df = 5 p = 0.048

    At alpha = 0.05, what conclusion?

    • A

      Reject H0; data inconsistent with claimed distribution

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    • B

      Fail to reject H0

    • C

      Reject H0; data fit the distribution

    • D

      Accept H0

    Why

    Since p = 0.048 < 0.05, reject H0. There is evidence the observed counts are inconsistent with the hypothesized distribution.

  2. Sample 2difficulty 2/5

    A chi-square goodness-of-fit test yields chi-square = 5.6 with df = 4 and p-value = 0.231 at alpha = 0.05.

    df=4, p=0.231 5.6

    What is the correct conclusion?

    • A

      Fail to reject H0; insufficient evidence to conclude observed counts differ from claimed distribution

      check_circle
    • B

      Reject H0; the distribution matches

    • C

      Reject H0; the distribution differs

    • D

      Accept the alternative

    Why

    Since p-value (0.231) > alpha (0.05), fail to reject H0. There is not enough evidence to conclude the observed counts differ from the hypothesized distribution.

  3. Sample 3difficulty 3/5

    χ² is a sum of contributions, each ≥ 0. So χ² is

    • A

      Always > 1

    • B

      Always ≥ 0

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    • C

      Either sign

    • D

      Always negative

    Why

    Each (O−E)²/E ≥ 0; their sum cannot be negative.

  4. Sample 4difficulty 3/5

    χ² calculated = 7.81 with df=3 at α = 0.05 (critical = 7.81)

    • A

      Insufficient information

    • B

      Reject H₀ (just at the boundary)

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    • C

      Always reject

    • D

      Always fail to reject

    Why

    Equality means p ≈ α; conventionally treated as borderline reject.

  5. Sample 5difficulty 3/5

    χ² (right-skewed for small df)

    The χ² distribution is

    • A

      Uniform

    • B

      Bimodal

    • C

      Skewed right (always non-negative)

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    • D

      Symmetric

    Why

    χ² is non-negative and right-skewed; it becomes more symmetric as df grows.