help for relyplot

Reliability Plot

relyplot [if exp] [in range],
fractions(3,4,5,or 10) or groups(#)
[ci graph_options]

Description

relyplot examines reliability of predicted risks following a logistic
model. It creates categories of predicted risk, divided either into
fractions, e.g. tenths, or any number of equal size groups
(percentiles). It then calculates proportions of observed "events"
among subjects within similar predictive probability categories. These
proportions are plotted against a diagonal line for perfect fit
(observed=predicted). Deviations from the line indicate worse prediction
in those categories. relyplot can be repeated on a new sample using
logistic regression estimates from another sample.

Options required (must choose one only)

fractions(#) -- divides predicted risk into fractional categories of
risk. Only groups with observations are displayed. The following values are
allowed:

3 -- divides risk groups into thirds (0-.33, .33-.67, .67-1.0)
4 -- divides risk groups into fourths (0-.25, .25-.50, .50-.75, etc.)
5 -- divides risk groups into fifths (0-.20, .20-.40, .40-.60, etc.)
10 -- divides risk groups into tenths (0-.10, .10-.20, .20-.30, etc.)

groups(#) -- divides predicted risk into percentiles, i.e., # of equal
size groups; this would be useful if using fractions (see fractions) results
in too few observations in some groups to accurately calculate observed risk

Options

ci -- Plots the 95% confidence interval around the observed proportions

Examples

. use sample1
. logistic died chol age htn
. relyplot, fractions(10)

Displays a reliabilitly plot with predicted risks divided into tenths

. use sample2
. relyplot, fractions(10)

Opens a second data set, uses estimates from first data set

. relyplot, group(5)

Divides predicted risk into 5 equal size groups, i.e., quintiles