Statistical Sciences 2037A/B Lecture Notes - Standard Deviation, Confidence Interval
15 Jan 2013
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Document Summary
The most common confidence interval is 95% constructing a confidence interval is different depending on the type of question asked and the sample used. The most common way to construct a confidence interval is by using the margin of error. Chapter 21 role of confidence intervals in research. We need to distinguish between population standard deviation and the standard deviation for sample means (population standard deviation/sqrt(n)). The standard error of the mean (sem) is the same as standard deviation for sample means. To construct a confidence interval we need information. A confidence interval of 95% has the true population mean within 2 standard deviations (errors) of the sample mean. This should only be used with at least 30 observations or people. For 95% confidence for a smaller sample we use the t-distribution, which gives us a multiple larger than 2.
