Tag Archives: One quantitative variable

Confidence Interval for a Single Mean

A confidence interval for a single mean, specifically, is just a regular confidence interval that tries to estimate the possible mean of the population. Stattrek explains a confidence interval as “…to describe the amount of uncertainty associated with a sample estimate of a population parameter.”It’s not exact, and the higher percentage of confidence you want, the bigger the […]

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 […]


As one may know from either middle school or high school, the median is the value in the middle of a sample. That is, there is an equal number of values less than and more than the median. However, if the amount in the sample is an even number, the median is the average of the two […]


The median is one of two measures of center of one quantitative variable in summary statistics.When numbers in a data set are ordered sequentially, the median is the middle value in the total list of numbers. For the rest of the values in the data set, this means half of the numbers lie above the […]


A box plot, also known as a “box-and-whisker plot,” is a graph used to visually convey the distribution and variation of a single quantitative variable of a set of data on an interval. A box plot prominently features the quartiles, range and outliers of a set of data and can be drawn vertically or horizontally. The […]


The Boxplot or Box and Whisker Plot is a graph that is used to show the range data and where the outliers are expected to arise. The box section is the portion of the data between quartile 1 and quartile 3. There is generally a line inside the box, but not necessarily at the center, […]


A histogram is a graphical display for a single quantitative variable. The range of the quantitative variable is divided into intervals called bins which are plotted on the x-axis. Then either the frequency (number) or relative frequency (percentage) of data values falling within each bin is represented by the height of the bar sitting over […]