STAT 2510 Lecture Notes - Lecture 15: Confidence Interval, Point Estimation, Standard Deviation
7 Mar 2017
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Confidence intervals for one population mean when sigma is known. Confidence intervals requires three pieces of info: confidence level (95%, 90%, etc. , point estimate (usually x bar, margin of error (in each direction from point estimate) Confidence interval is determined by x bar plus/minus margin of error. Assumptions when sigma is known: simple random sampling, normal population or large sample, sigma known. Use z-table to find z to the right: confidence interval for mu: x bar plus/minus margin of error, interpret confidence interval. Fixed n: lower confidence level, lower margin of error, increase accuracies. Fixed confidence level: increase sample size, decrease margin of error, increase accuracy. T=distribution has different curves for each possible sample size. *curve is identified by degrees of freedom (df)=n-1. T-table: t subscript alpha has area to the right. One mean t-interval procedure: buiding a confidence interval around mu when sigma is unknown.
