What is the upper quartile of the distribution, if the semi-inter quartile range is 24 and the lower quartile is 18?
Answers
Answer:
In a set of data, the quartiles are the values that divide the data into four equal parts. The median of a set of data separates the set in half.
The median of the lower half of a set of data is the lower quartile ( LQ ) or Q1 .
The median of the upper half of a set of data is the upper quartile ( UQ ) or Q3 .
The upper and lower quartiles can be used to find another measure of variation call the interquartile range .
The interquartile range or IQR is the range of the middle half of a set of data. It is the difference between the upper quartile and the lower quartile.
Interquartile range = Q3−Q1
In the above example, the lower quartile is 52 and the upper quartile is 58 .
The interquartile range is 58−52 or 6 .
Data that is more than 1.5 times the value of the interquartile range beyond the quartiles are called outliers .
Statisticians sometimes also use the terms semi-interquartile range and mid-quartile range .
The semi-interquartile range is one-half the difference between the first and third quartiles. It is half the distance needed to cover half the scores. The semi-interquartile range is affected very little by extreme scores. This makes it a good measure of spread for skewed distributions. It is obtained by evaluating Q3−Q12 .
The mid-quartile range is the numerical value midway between the first and third quartile. It is one-half the sum of the first and third quartiles. It is obtained by evaluating Q3+Q12 .