Use simple random sampling to select observations from a sampling frame

To use the sampling tool, select a data set where each row in the
data set is unique (i.e., no duplicates). A dataset that fits these
requirements is bundled with Radiant and is available through the
*Data > Manage* tab (i.e., choose `Examples`

from
the `Load data of type`

drop-down and press
`Load`

). Select `rndnames`

from the
`Datasets`

dropdown.

`Names`

is a unique identifier in this dataset. If we
select this variable and choose the desired sample size, e.g., 10, list
of names of the desired length will be created.

How does this work? Each person in the data is assigned a random
number between 0 and 1 from a uniform distribution. Rows are then sorted
on that random number and the \(n\)
people from the list with the highest score are selected for the sample.
By using a random number, every respondent has the same probability of
being in the sample. For example, if we need a sample of 10 people from
the 100 included in the `rndnames`

dataset, each individual
has a 10% chances of being included in the sample. By default, the
random seed is set to `1234`

to ensure the sampling results
are reproducible. If there is no input in `Rnd. seed`

, the
selected rows will change every time we generate a sample.

The full list of 100 people is called the
`sampling frame`

. Ideally, this is a comprehensive list of
*all* sampling units (e.g., customers or companies) in your
target market. To determine the appropriate value for *n*, use
the sample size tools in the *Design* menu. To show the full
sampling frame, click on the `Show sampling frame`

check
box.

To download data for the generated sample in CSV format, click on the
icon in the top-right of
your screen. The created sample can also be stored in Radiant by
providing a name for the dataset and then clicking on the
`Store`

button.

Add code to
*Report
> Rmd* to (re)create the sample by clicking the
icon on the bottom
left of your screen or by pressing `ALT-enter`

on your
keyboard.

For an overview of related R-functions used by Radiant for sampling
and sample size calculations see
*Design
> Sample*

The key function from the `stats`

package used in the
`sampling`

tool is `runif`

. This function is used
to generate the random numbers assigned to each row in the available
data.