This can be accomplished in a number of ways.

**1) Use of the Expanded Form of the SAMPLE command to select only the ranges (months) needed.**

e.g. to select each August, assuming the series begins with February

```
sample 7 7 19 19 31 31 43 43 55 55
```

and so on for as many observations as you need.

**2) Via a SKIPIF command using a supplied month index**

Read monthly observations along with a month index from a free format text file, skip all but the 8th month indicated by the index, produce summary statistics for the subset and finally graph the variable.

```
read (testdata.txt) month variable
skipif(month.ne.8)
stat variable
graph variable
```

**3) Via a SKIPIF command using an index we generate**

Read monthly observations from a free format text file, create a month index, skip all but the 8th month indicated by the index, produce summary statistics for the subset and finally graph the variable formatting the x axis to show the month counter.

```
* Assuming we have monthly observations stored in a free format text file
* where the 1st observation is a February. Counter is from 1...N.
read (testdata1.txt) variable
* Generate month index noting the data starts from February
* TIME(1) creates an index by adding 1 to each value.
* MOD(12,12) = 0 so replace all 0s with 12
genr month_ind=mod(time(1),12)
if(month_ind.eq.0) month_ind = 12
* Create a time index for the graph axis and adjust for start of February
time 2007 12 months
genr month = lag(months,-1)
* Skip any observations we do not want to use in estimation or graphing
set nowarnskip
skipif(month_ind.ne.8)
* Check basic statistics of the variable for just the 8th month
stat variable
* Draw a Graph
* Use the TIMEFMT and AXISFMT commands to customise the X axis
* Plot against the corrected month index
timefmt %Y.%m
axisfmt %m/%Y
graph variable month / timefmt axisfmt line
```

The output from this is:

```
|_stat variable
NAME N MEAN ST. DEV VARIANCE MINIMUM MAXIMUM
VARIABLE 4 0.16307E+08 0.15739E+08 0.24772E+15 0.11308E+06 0.36045E+08
```

The graph produced was:

The data file used in this was:
testdata1.txt