Chapter 8 - Chapter 8 Measuring In this chapter Validity...

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Chapter 8 Measuring In this chapter Validity and reliability Types of data Levels of measure Validity and reliability Validity – a measurement is valid if it actually measures what it claims to measure Often a rate (percent) at which something occurs is a more valid measure than a frequency Example Suppose you are interested in looking at the pattern of homicides in the U.S. over time. If you look at the number of homicides from 1970 to present in order to investigate the pattern is this a valid measure? The answer is no because the U.S. population is growing over time. The number of homicides will increase simply because of this increased population. The rate or percent of homicides in the U.S. is more valid measure. Reliability – a measurement is reliable if it is the same time after time (small variability) Variability – Consistency across measures Example Suppose we are interested in measuring weight with a scale and the scale always weighs 10 pounds more than it should. Is the scale reliable? Is the scale valid?
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This note was uploaded on 07/12/2011 for the course STATS 200 taught by Professor Bradley,w during the Fall '10 term at KCTCS.

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Chapter 8 - Chapter 8 Measuring In this chapter Validity...

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