Basic Analysis and Graphing - SAS

Chapter 5 Performing Oneway Analysis 161
CDF Plot
CDF Plot
A CDF plot shows the cumulative distribution function for all of the groups in the Oneway report. CDF
plots are useful if you want to compare the distributions of the response across levels of the X factor.
Related Information
• “Example of a CDF Plot” on page 175
Densities
The Densities options provide several ways to compare the distribution and composition of the response
across the levels of the X factor. There are three density options:
• Compare Densities shows a smooth curve estimating the density of each group. The smooth curve is
the kernel density estimate for each group.
• Composition of Densities shows the summed densities, weighted by each group’s counts. At each X
value, the Composition of Densities plot shows how each group contributes to the total.
• Proportion of Densities shows the contribution of the group as a proportion of the total at each X level.
Related Information
• “Example of the Densities Options” on page 176
Matching Column
Use the Matching Column option to specify a matching (ID) variable for a matching model analysis. The
Matching Column option addresses the case when the data in a one-way analysis come from matched
(paired) data, such as when observations in different groups come from the same subject.
Note: A special case of matching leads to the paired t-test. The Matched Pairs platform handles this type
of data, but the data must be organized with the pairs in different columns, not in different rows.
The Matching Column option performs two primary actions:
• It fits an additive model (using an iterative proportional fitting algorithm) that includes both the
grouping variable (the X variable in the Fit Y by X analysis) and the matching variable that you select.
The iterative proportional fitting algorithm makes a difference if there are hundreds of subjects, because
the equivalent linear model would be very slow and would require huge memory resources.
• It draws lines between the points that match across the groups. If there are multiple observations with
the same matching ID value, lines are drawn from the mean of the group of observations.
The Matching Column option automatically activates the Matching Lines option connecting the matching
points. To turn the lines off, select Display Options > Matching Lines.