STA291. Statistical Methods Lecture 9. About those boxplots …. Often used to compare samples (& make inferences about populations) Example: Barry Bonds’ home runs. Boxplots or other graphs used for comparison/outlier checking:. The good: Quick Simple
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Often used to compare samples (& make inferences about populations)
Example: Barry Bonds’ home runs
Often used to standardize individual values, either within samples/populations or between them, the z-score, or standardized score:
is the number of standard deviations an observation is away from its mean.
Since both the population or sample versions of the z-score use the mean and standard deviation, we have the same concern when calculating it that we did when using the mean to describe the center of a distribution or the standard deviation to describe its variability.
While it can be and sometimes is used in describing/comparing observations in the absence of knowledge about the distribution, more properly done so having determined that we have a “roughly symmetric and mound-shaped” distribution.
Distribution of SAT score is scaled to be
approximately bell-shaped with mean 500
and standard deviation 100
About 68% of the scores are between __ ?
About 95% are between ____ ?
If you have a score above 700, you are in the top ___________%?