# Random Samples

A simple way to randomly select observations from your data.
At the end you can see how to randomly order (permute) your data.

### To randomly select a sample of
size *n* from data in a column.

Here the data is executive compensation: www.oswego.edu/`srp/stats/comp1f04.txt.

Column 1 is the sector the CEO works in; column 2 is his/her
total compensation.

Begin by accessing the “Sample from columns” command.

The columns c3 and c4 have names already set up. In this
operation we’ll choose 10 of the rows in c1 and c2 at random, and place those
rows in c3 and c4. c3 and c4 will then constitute a random sample of 10.

This is the proper way to fill in the dialog. DO NOT check
the sample with replacement box UNLESS you want to entertain the possibility of
sampling the same row twice. In almost all applications the sampling is done
without replacement. Click OK.

When you’ve finished you will have a 10 row fill in columns c3
and c4.

You should try this on your own. You will get a different
result in columns c3 and c4 – because the sample is chosen randomly.

After this, you can check if you like to find which row(s)
were chosen. This can be somewhat tedious – although if you select c2 and
right-click to “Find”, you can locate values quickly enough:

We can see here that row 1279 was the first row in the
random selection.

### Note:

It is not necessary to specify two columns for input (and
output). In this example information from both columns 1 and 2 were taken into
columns 3 and 4. If you were not interested in the Sector information (C1) you
could sample from column c2 (only), storing the sample in column c3 (only).

It *is* necessary to specify the *same* number of
columns in both boxes in the dialog.

### To permute (order) your data
randomly

To randomly order your data simply sample the same number of
rows as there are rows in the data. For example, with the compensation data,
for which there are 1422 rows, you would “Sample **1422** rows…”