STATISTICAL TECHNIQUES AND TOOLS
MEASURES OF VARIABILITY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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What is the difference between the formulas for population variance and sample variance?
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The sample variance is the square root of the population variance.
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The population variance divides the sum of the squares by n-1, while sample divides by N.
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The population variance divides the sum of the squares by N, while sample divides by n-1.
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There is no difference.
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Explanation:
Detailed explanation-1: -So, when we use N instead of N-1, we have an error called statistical bias, which means that the sample variance (the estimator) is systematically different from the true population parameter (in this case, the variance).
Detailed explanation-2: -Sample variance refers to variation of observations (the data points) in a single sample. Sampling variance refers to variation of a particular statistic (e.g. the mean) calculated in sample, if to repeat the study (sample-creation/data-collection/statistic-calculation) many times.
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