Percentiles
This article explores percentiles. Percentiles split the data into 100 parts. A percentile (or a centile) is a measure used in statistics indicating the value below which a given percentage of collected data fall. For example, the 20th percentile is the value below which 20 percent of the observations may be found.
Quick summary
- To calculate the xth percentile Px, we find the value of the xn/100 th term.
- The interquartile range is the 25% to 75% interpercentile range. The n% to m% interpercentile range = Pm – Pn
Example: The height in cm of 70boys were recorded. The results are shown in the table below.
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Calculate;
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Calculate;
- the 90th percentile
- the 10th percentile
- the 10% to 90% interpercentile range
Answer
- P90 is the value of the;
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We must use interpolation;
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-
10% to 90% interpercentile range
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This means 90% – 10% = 90% of the data lie within 25.3cm
