Measures of position that divide a set of data into four equal parts
Grouped data
Data formed by aggregating individual observations of a variable into groups, so that a frequency distribution of these groups serves as a convenient means of summarizing or analyzing the data
Frequency distribution table shows the class intervals, scores, and frequency
Lower boundary (LB)
The lower limit of each class interval
Less than cumulative frequency (<cf)
The cumulative frequency up to the class before the current one
Formula for quartile
Qk class = kn/4
Qk = LB + (kn/4 - <cfb) / fQk * i
LB = lower boundary of the Qk class
n = total frequency
<cfb = less than cumulative frequency before the Qk class
