types of data and visual representations

bar chart

Graph with vertical or horizontal columns, also called a column graph.

bimodal

A graph with 2 peaks.

box plot

Graphical display of five-number summary, also called a box-and-whisker plot.

categorical data

Data that are named by categories.

continuous data

Numerical data that can take any value that lies within an interval.

decile

One of the values that divide a data set into 10 equal parts.

discrete data

Numerical data that can only take specific distinct values.

dot plot

A column graph of dots.

five-number summary

The lowest and highest values, median, and lower and upper quartiles of a data set.

frequency polygon

Frequency line graph.

histogram

Bar chart of frequencies with no gap between columns.

interquartile range

Measure of spread, the difference between the upper and lower quartiles.

mean

Average score, calculated by dividing the sum of scores by the total number of scores.

median

The middle score when all scores are placed in order.

modality

The number of peaks in a set of data.

mode

The score with the highest frequency.

multimodal

Having many peaks in a set of data.

nominal data

Categorical data that is listed by name with no order.

numerical data

Data whose values are numbers.

ogive

Cumulative frequency polygon.

ordinal data

Categorical data that can be ordered.

outlier

A score that is clearly apart from other scores - it may be much higher or lower than the other scores.

Pareto chart

A chart containing both a bar chart and a line graph where individual values are represented in descending order by the bars and the cumulative total is represented by the line graph.

percentile

One of the values that divide a data set into 100 equal parts.

pie chart

Circular graph showing categories as sectors.

quantile

One of the values that divide a data set into equal parts.

quartile

One of the values that divide a data set into 4 equal parts.

range

Difference between the highest and lowest scores.

skewness

The shape or asymmetry of a graph to one side.

standard deviation

Measure of the spread of data values from the mean. The square root of variance.

stem-and-leaf plot

Graphical display of tens (stem) and units (leaves).

symmetrical distribution

A distribution where the left and right sides are mirror images of each other.

two-way table

A table that combines the effects of 2 separate variables (usually categorical).

variance

Measure of spread, the square of standard deviation.