Chisquare tests are common in genetics. A gene called ACTN3 encodes a protein which functions in fasttwitch muscles. People have different variants of this gene, classified as RR, RX, or XX. Computer output is shown for testing whether the proportions in these categories are 0.25, 0.50, and 0.25, respectively. The observed counts come from a study conducted in Australia.

(a) What is the sample size?
(b) What is the observed number of people with the variant RR for this gene? What is the expected number of people in this group under H₀?
(c) Which variant contributes the most to the chisquare statistic? For this variant, is the observed value greater than or less than expected?

(d) What are the degrees of freedom for the test?
(e) What is the p-value? Give the conclusion of the test in context.

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Chi-Square Goodness-of-Fit Test for Observed Counts Test Proportion 0.25 Contribution to Chi-Sq 4.04587 0.29358 7.71560 Observed Expected Category 109 RR 130 226 RX 0.50 0.25 218 109 80 XX Chi-Sq P-Value 0.002 2 12.0550 DF 436