Percentile - Q 2 ) is defined as the 50th percentile, which...

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Percentile The  N th  percentile  is defined as the value such that  N  percent of the values lie below it. So, for  example, a score of 5 percent from the top score would be the 95th percentile because it is above 95  percent of the other scores (see Figure 4).  Figure 4. Ninety-five percent of the test scores are less than the value of the 95th percentile. Quartiles and interquartile range The  lower quartile  (  Q 1 ) is defined as the 25th percentile; thus, 75 percent of the measures are  above the lower quartile. The  middle quartile  ( 
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Unformatted text preview: Q 2 ) is defined as the 50th percentile, which is, in fact, the median of all the measures. The upper quartile ( Q 3 ) is defined as the 75th percentile; thus, only 25 percent of the measures are above the upper quartile. The interquartile range ( IQR ) is the value for Q 3 Q 1 . Like the range, it is a single value. Figure 5 illustrates the locations of the median and the quartiles for a set of 20 test scores. Figure 5. An illustration of the quartiles and the interquartile range....
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