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Quiz 2.1 to 2.3
Chapter 2  Day 4
Overall Notes

There is one version of this assessment provided in the Teacher Resources Materials (TRM). Use this assessment asis or use it as a model to create your own.

If you are making your own assessment, consider using the test bank and the ExamView software.
Common Student Errors

When interpreting a percentile, students often say “in” the 80th percentile, rather than “at” the 80th percentile. This is worth making a note to them, but we still give them full credit.

When calculating a zscore, students will sometimes input the numbers into the calculator incorrectly as 90 – 80 / 4 = 70, instead of (90 – 80) / 4 = 2.5.

When interpreting a zscore, a response of “1.43 above the mean” is incorrect. A zscore is measuring the number of standard deviations above or below the mean.

When interpreting a zscore, students sometimes forget to include a direction. A good interpretation should always state the number of standard deviations above or below the mean.

When adding or subtracting a constant to a set of quantitative data, students will often incorrectly add or subtract the constant from the standard deviation. Remember that a shift of the data to the left or right does not change any of the measures of variability.

Students often confuse left and right skew. The direction of the skew is the direction the distribution is being pulled.
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