Random sampling from populations

Random sampling of animals

Sample size

Sampling with or without replacement?

Sampling with replacement

Sampling without replacement

Paste columns of data for the sampling frame in the space below and click on submit. The first column must be a unique id for each cluster (owner, pen number etc), the second the number of units for each cluster. Include a header row containing column headings for the data.

Download example data

Submit

Select a random sample of units from a sampling frame of a clustered population (for example, animals with different owners in a village, pigs in pens in a piggery, cattle in pens in a feedlot, etc). A full sampling frame of all units is generated with units in each cluster numbered sequentially. Simple random sampling is then done to generate a sample with units identified by cluster id and then by sequential number for each cluster.

Sampling can be based on either a specified number of units to be sampled or a specified proportion of the total number of units in the sampling frame. Sampling can also be with or without (default) replacement.

A list of all clusters and the number of units in each cluster is required for generation of the sampling frame. This can be copied and pasted from excel or other software and should be formatted as two columns: the first column is the unique cluster id and the second is the number of units in each cluster.

Sample size should be entered as an integer number of units to be sampled or a proportion (>0 and <1) of the total population to be sampled.

Download and check out the example data if you are unsure what is required.

Please note: very large sampling frames may take several minutes to process, so please be patient.