![]() Chapter Contents |
![]() Previous |
![]() Next |
Distribution Analyses |
For the normal distribution, you can specify your own and
parameters from the Fit Parametric menu.
Otherwise, you can use the sample mean and standard deviation
as estimates for
and
by selecting
Fit Parametric:Normal in the cumulative distribution options dialog
or by choosing Distribution:Normal and
Method:Sample Estimates/MLE
in the Parametric CDF Estimation dialog.
For the lognormal, exponential, and Weibull distributions,
you can specify your own threshold parameter
and have the remaining parameters estimated by the maximum-
likelihood method, or you can specify all the distribution
parameters in the Parametric CDF Estimation dialog.
Otherwise, you can have the threshold parameter
set to 0 and the remaining parameters estimated
by the maximum-likelihood method.
To do this, select Lognormal, Exponential, or Weibull
in the Cumulative Distribution Output dialog or choose
Method:Sample Estimates/MLE and Parameter:MLE, Theta:0
in the Parametric CDF Estimation dialog.
If you select a Weight variable, only normal CDF can be created.
For Method:Sample Estimates/MLE,
and sw
are used to display the cumulative distribution function
with vardef=WDF/WGT;
and sa
are used with vardef=DF/N.
For Method:Specification, the values in the entry fields
Mean/Theta and Sigma are used to display the
cumulative distribution function with vardef=WDF/WGT;
the values of Mean/Theta and Sigma/
are used with vardef=DF/N.
Figure 38.30 displays a normal distribution
function with = 58.4333 (the sample mean) and
= 8.2807 (the sample standard deviation);
it also displays a lognormal distribution function with
= 30 and
and
estimated by the MLE.
Use sliders to change the CDF estimate.
When MLE is used for the lognormal, exponential, and
Weibull distributions, changing the value of in the slider also causes the remaining parameters
to be estimated by the MLE for the new
.
![]() Chapter Contents |
![]() Previous |
![]() Next |
![]() Top |
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.