What does a cumalative frequency graph compare?
Yes. Find the median, which is the value corresponding to a cumulative frequency of 50% of the sample/population size, and the lower and upper quartile, which correspond to 25% and 75% respectively. From this the interquartile range can be calculated (upper quartile – lower quartile) . Median is a measure of location (average) and interquartile range is a measure of dispersion (spread). So two or more sets of data can be compared. For instance you might find that boys are taller than girls (on average) and that the variation of height is greater for boys than girls. (I don’t know if this is true: it’s just an example.) To answer your question, a single cumulative frequency curve doesn’t compare anything. Two cumulative frequncy curves can be used to compare median (“average”) and dispersion (“spread”). But this comparison is only meaningful if they are for the same factor (variable) but with different samples or populations. To compare different factors, it is better to use a scatter g
