# Author Archives: Newman Knowlton

## Confidence Interval for Two Independent Proportions

A confidence interval for two independent proportions is a tool used in inferential statistics to estimate a proportional* difference between two independent populations. These two populations must be distinguished by a single binary categorical variable; e.g. sex (male or female), but not blood type (A, B, AB, or O). With this information, it can be […]

## Interquartile Range (IQR)

The interquartile range (IQR) is a measure of the spread of a distribution of a single quantitative variable. The IQR is a rather simple calculation and is merely the difference between (hence “range”) the upper quartile (Q3) and the lower quartile (Q1) (hence “inter” and “quartile”). For a better understanding of quartiles, here is a site […]

## Side-By-Side Boxplots

Also known as a parallel boxplot or comparative boxplot, a  side-by-side boxplot is a visual display comparing the levels (the possible values) of one categorical variable by means of a quantitative variable. As its name implies, the side-by-side boxplot is constructed by placing single boxplots adjacent to one another on a single scale. A side-by-side […]