Question

A researcher tests a sample of first-grade children for a school district to help the district identify areas in which the curriculum should be changed. The measure is a valid and reliable measure of intelligence. The researcher estimates the population mean for the intelligence scores and observes a large value for the standard error of the mean. The best thing the researcher could do to improve the estimate is
A. test children in a different, more heterogeneous school district.
B. compute a confidence interval.
C. change the testing procedures to increase the variability of the test scores.
D. increase the sample size of children tested.

Answer

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