Copyright 2007 N Ahbel Standard Deviation Standard Deviation
Copyright © 2007, N. Ahbel Standard Deviation
• Standard Deviation from the mean • The most commonly used measure of spread for uni-variate data • Measured in the same units as the data (like the mean) Copyright © 2007, N. Ahbel Standard Deviation
• Qualitative description Standard deviation from the mean Typical distance from the mean • Consider these quiz scores (points): 9, 8, 7, 6, 9, 10, 8, 9, 9, 10 with a mean of 8. 5 points. What is a typical distance from the mean? • A little more than 1 point Copyright © 2007, N. Ahbel Standard Deviation
• If we can collect data from the entire population, we report the population mean and population std. dev. • Most often we can only get a sample set of data from the entire population and then we report the sample mean and sample std. dev. • Notation: Sample Mean Std. dev. Population μ s σ Copyright © 2007, N. Ahbel Population vs. Sample
• Quantitative definition: When collecting data for variable x having values x 1, x 2, x 3, …, x. N μ)2 You will not be responsible for knowing these formulae in this course, but you will likely study them in detail when you take a full course in statistics. Note: “std. Dev()” in Fathom is s, the sample std. dev. Copyright © 2007, N. Ahbel Standard Deviation
Copyright © 2007, N. Ahbel Standard Deviation
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