Glossary
Continuous Variables
Quantitative variables that can take on any value within a given range, often involving measurements.
Example:
A student's exact height in centimeters is a continuous variable because it can be 165.5 cm, 165.53 cm, or any value in between.
Discrete Variables
Quantitative variables whose possible values can be counted or listed, often representing whole numbers.
Example:
The number of cars in a school parking lot each morning is a discrete variable because you can count them as 0, 1, 2, and so on.
Dotplot
A simple graphical display for quantitative data where each data point is represented by a dot above a number line, with dots stacked for repeated values.
Example:
A dotplot of the number of hours students slept before an exam would clearly show clusters of common sleep times and any outliers.
Frequency Polygon
A line graph that displays the distribution of quantitative data by plotting points at the midpoints of each bin's frequency and connecting them with lines.
Example:
To compare the distribution of daily temperatures in two different cities over a month, you could use a frequency polygon for each city on the same graph.
Histogram
A graphical display that uses bars to show the distribution of quantitative data, where the data is grouped into 'bins' and the height of each bar represents the frequency of values in that bin.
Example:
A histogram of the ages of people attending a concert might show a peak for attendees in their 20s, indicating a younger audience.
Ogive
Also known as a cumulative frequency plot, an ogive shows the cumulative frequency or cumulative relative frequency of data, indicating the number or proportion of data points less than or equal to a given value.
Example:
An ogive for student test scores could quickly show that 70% of students scored 85 or below, making it easy to identify percentiles.
Quantitative Data
Data that consists of numerical values that can be measured or counted, representing quantities or amounts.
Example:
The number of minutes a student spends studying for an exam is an example of quantitative data.
Stem-and-Leaf Plot
A graphical display that organizes quantitative data by separating each value into a 'stem' (leading digit(s)) and a 'leaf' (trailing digit), preserving the individual data values.
Example:
A stem-and-leaf plot of the number of push-ups students can do might show '2 | 3 5 8' representing 23, 25, and 28 push-ups.