STATS 2B03 Chapter Notes - Chapter 6: Confidence Interval, Standard Deviation, Sampling Distribution
19 Jun 2013
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Probabilistic interpretation: in repeated sampling, from a normally distributed population with a known standard deviation, 100(1 ) percent of all intervals of the form will in the long run include the population mean. Practical interpretation: when sampling is from a normally distributed population with known standard deviation, we are 100( percent confident that the single computed interval. Precision: quantity obtained by multiplying the reliability factor by the standard error of the mean. Sampling from nonnormal populations: for large samples, the sampling population distribution of is approximately normally distributed. Alternative estimates of central tendency: median is sometimes preferred over the mean as a measure of central tendency when outliers are present. Trimmed mean: estimators that are insensitive to outliers are called robust estimators. Another robust measure and estimator of central tendency is the trimmed mean: Discard the smallest 100 percent and the largest 100 percent of the measurements. The recommended value of is something between . 1 and . 2.
