Question

The following blood-type frequencies were obtained from a sample of 1000 subjects.

Blood Type:	O	A	B	AB	Total
Frequency:	465	394	96	45	1000

An appropriate hypothesis test is conducted to test whether the data is consistent with the claim that in this population, blood types O, A, B and AB have proportions 0.45, 0.4, 0.1, and 0.05, respectively. The resultant test statistic and associated p-value are 1.25 and 0.741 respectively.

The test statistic should be compared to which null distribution:

		the chi-squared distribution with 4 degrees of freedom
		the chi-squared distribution with 3 degrees of freedom
		the t distribution with 3 degrees of freedom
		the t distribution with 999 degrees of freedom
		the binomial distribution
		the standard normal distribution

Answer 1

Answer: The chi-squared distribution with 3 degrees of freedom

Explanation: The degrees of freedom for chi-square test = n – 1 = 4-1=3

Thus the test statistic should be compared to chi-squared distribution with 3 degrees of freedom