A Researcher Tests a Sample of First-Grade Children for a School

Multiple Choice

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) increase the sample size of children tested.
D) change the testing procedures to increase the variability of the test scores.