1. Quick Data Summaries in SAS
Start by bringing in data
Use permanent data set for these examples
Proc Summary
Produces summaries relatively easily
Designed to produce a table of output that can be manipulated further ***This is a critical difference from tabulate***
Need to pre-sort data by any “by” groups
Need to print out results

2. Quick Data Summaries in SAS
Basic Summary Syntax:
Proc sort;
By var1 var2;
Run;
Proc summary;
Var variable3;
Output out=new_table mean=mean_name n=n_name….;
Proc print;

3. Statistics available in Proc Summary
Mean, n, standard deviation, standard deviation, variance, coefficient of variation, sum
Minimum, maximum, range, number of missing observations, median

4. Some Quirks of Proc Summary
Whenever you use proc summary, it adds two new variables: _type_ and _freq_ (note underscores at beginning and end of variable names
_freq_ indicates the number of observations
_type_ indicates whether the output is a matrix or not
You can ignore these variables in virtually all cases
You need to remember what is the “active” dataset, or specify the dataset that summary will operate on
The active dataset is the most recently used dataset by default

5. Shannon’s Diversity Index
H= -∑ pi ln(pi)