Why is variability among people, which translates to variability in your data, an important consideration in your decision of how large a sample to use in your research?
What will be an ideal response?
When people are similar to one another, they are less likely to differ in their scores on the DV. As such, a variable that has a small effect might be easier to spot People in a given group don't differ, so they have similar scores with no treatment. A small effect will be easier to see because differences will be due to the treatment rather than due to measurement error.
When people differ from one another, you often expect differences that don't mean anything. Thus, a small difference due to an IV is hidden by the naturally occurring differences between groups.
Thus, if your groups are heterogeneous (i.e., variable), producing a lot of difference even in the absence of the IV, you need a larger sample to be confident that the IV made a difference. On the other hand, if your groups are similar, you don't need such a large sample because small differences stand out more.
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What did No Child Left Behind, passed in 2001, do?
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Nuclear power plants in the U.S. cluster in
a. the Northwest. b. the Southwest. c. eastern states. d. western states.
Talk radio has long been dominated by
A) moderates. B) ?liberals. C) ?conservatives. ? D) ?anarchists.