Step Charts

Graph > Chart > Step

 

step1

A step chart is a special form of line chart which is useful for displaying changing numeric values over a period of time. The (horizontal) x-axis in a step line chart represents a period of time, and values are plotted on the (vertical) Y-axis at constant or irregular time intervals.

step2

 

 

Dialog box items

Categorical Variable:
Variable that defines the categories shown on the chart. There is one point on the line for each value of the variable. This axis is a category axis that display categorical data.

Define Steps by (optional):
Variable (optional) that defines the lines. There is one line for each value of the variable. This option is only required for multiple steps.

Steps Represent:
Select one of the alternatives in the Lines Represent group to specify how the data are represented on the scale axis.

oCount: The value graphed represents the number of cases in each category.

oPercentage: The value graphed represents the number of cases in each category, expressed as a percentage of the total number of cases.

oOther summary function: The value graphed represents the function displayed for the selected variable. To specify a different function, click the drop-down button. The selected variable must be numeric.

 

Data

To chart counts of unique values, you need one column of categorical variable to be counted. Each row of data should represent a single observation. To plot a function of a variable, you also need a column of continuous data.

 

 

Options

Data Labels:
Use to label each data point. After creating a chart, you can change the data labels or their attributes, or add data labels (see Editing Labels).
Select one of the alternatives:

oNone: Choose to suppress data labels

oY-value Labels: Choose to label each point with its y-axis value.

Data Options

oExclude missing values: Check to excludes rows that have missing values.

oShow ToolTip: Check to display messages in a ToolTip window.

 

 

Example

Subjects were students in grades 4-6 from three school districts in Ingham and Clinton Counties, Michigan. Chase and Dummer stratified their sample, selecting students from urban, suburban, and rural school districts with approximately 1/3 of their sample coming from each district. Students indicated whether good grades, athletic ability, or popularity was most important to them. They also ranked four factors: grades, sports, looks, and money, in order of their importance for popularity. The questionnaire also asked for gender, grade level, and other demographic information.

Source: http://lib.stat.cmu.edu/DASL/Datafiles/PopularKids.html

 

1.Open the DataBook summary.vstz

2.Select the sheet PopularKids

3.Choose the tab Graph, and then the group Chart, which displays a collection of gallery of items

4.Select Step and then use tool-tip to select Step Chart Using Symbols.
All available command is displayed in the gallery of graphics

5.Select group Data

6.In Categorical Variable, select Grades.

7.Click Finish

 

 

Chart window output

step11