STATISTICAL GRAPHS

Frequency Distribution Choose a number of classes. Calculate the data range. Determine the class width. Calculate the class limits. Tally the data. Fill in the frequencies. Label the chart.

Possible Extra Features class midpoint column relative frequency column cumulative frequency column

Frequency Histogram Calculate class boundaries, or use midpoints, and mark the horizontal scale. Choose an appropriate vertical scale for the frequencies. Draw the bars. Label the graph and its axes. Options: use relative or cumulative frequencies

Frequency Polygon Start the horizontal axis on a midpoint value one class width below the first class midpoint, and end it one above the last. (The polygon must begin and end on the horizontal axis where the frequency is zero.) The vertical axis shows the frequency. Plot points. (midpoint, frequency) Connect the points with line segments. Label the axes and the graph.

Cumulative Frequency Graph (Ogive) Start the horizontal axis on the lower class boundary of the first class. Include all the upper class boundaries. The vertical axis shows cumulative frequency or cumulative relative frequency. Plot points. (upper class boundaries, cumulative frequency) The first point should be on the horizontal axis, and the cumulative frequency of the last point should be the sample size. Connect the points with line segments. Label the axes and the graph.

Stem-and-Leaf Plot Split the numbers. The right digit becomes the leaf and the left digit(s) are the stems. List the “stems” in a vertical line. List all the “leaves” in rows to the right of their respective stems. The result is an unordered plot. Rearrange the leaves to put them in numerical order. Keep the leaves organized in columns as well as rows. Label the plot and include a key showing what number a stem and its leaf represent.

Dot Plot Make a horizontal number line so that its scale includes all the data values. Place a dot to represent each data value over the corresponding value on the number line. Stack dots vertically for repeated values, maintaining equal spacing. Label the plot.

Pie Chart You know this one already!

Pareto Chart Make a bar graph with frequencies or relative frequencies. Put the bars in order of decreasing height with the tallest bar on the left. Label the axes and graph.

Scatter Plot Graph data points. Label the axes and graph.

Time Series Chart The horizontal axis shows time or date. The vertical axis shows the value measured. Plot points. Connect the points with line segments. Label the axes and graph.