Topic 16

# Topic 16 - Topic 16 Poli 311 November 15th 2011 Validity...

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Topic 16 : Poli 311 November 15 th 2011 Validity and Reliability How well the empirical indicators represent that theoretical concepts. Never take for granted the indicators when you are reading a research or doing one. Validity : how do we measure what we are measuring Reliability : if we repeat the measurements on same cases and same conditions we must have the same results. Reliability is very important. We can’t have validity without reliability. Measurement error : we have to assume there is a measurement error . Differences in values assign to cases do not reflect the difference in measurement cases. Systematic Error: Constant errors They arise when measurement is picking up some other differences in characteristics then the ones we are trying to measure If systematic errors are present we can’t have good measurement They do not cancel one another out Random Error: Affect different aspect ( each application of the measurement) Chance makes the measurement unreliable , they occur due to something transient like

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## This note was uploaded on 02/06/2012 for the course POLI POLI-311-0 taught by Professor Melaneethomas during the Fall '10 term at McGill.

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Topic 16 - Topic 16 Poli 311 November 15th 2011 Validity...

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