Take Random or Periodic Samples in Gnumeric

Gnumeric’s Sampling Tool can draw a random subset of records or a periodic sample that selects observations at regular intervals. Those methods answer different questions and can introduce different kinds of bias.

Prepare a numbered population

Download 20 numbered records. Each record has an ID from 1 through 20. Keep the ID and Measurement columns together if each row represents one observation.

Periodic sampling example

A period of 4 means selecting every fourth observation. If a demonstration begins at ID 1, the displayed IDs would be 1, 5, 9, 13, 17 (five records). However, the exact starting offset and row handling in Gnumeric’s tool should be checked in your installed release; the documented method guarantees the spacing principle, not that an arbitrary offset is always one.

Use Gnumeric’s Sampling Tool

1. Select the input range and locate Sampling within the Statistics menu tools.
2. If the first row contains headings, use the Labels option as described by the Gnumeric manual.
3. Choose Random for a sample selected without fixed periodic positions; supply the desired sample size.
4. Alternatively choose Periodic and specify the period (for this exercise, 4).
5. Send results to a new area or sheet, keeping the source data intact.
6. Check the number of resulting observations and confirm the original source rows were not accidentally reordered.

Why random and periodic samples are not interchangeable

Random sample: exact selected IDs can change from run to run, so don’t promise a fixed list. Use a reproducible random seed where the selected software/tool supports one.

Periodic sample: if every fourth record is chosen from a dataset with a repeating four-row pattern, your sample can be badly biased. Examine the original ordering before choosing a period.

Sampling rows from a two-column table is also different from sampling independent cells in each column: keep observations paired if columns describe the same record.

Related: Gnumeric descriptive statistics describes the sampled measurements; Gnumeric ANOVA compares groups under additional assumptions.

Verification: The 20-row file and demonstration positions were checked independently. Gnumeric’s tool has not been run, so actual periodic offset/labels must be verified before publication.

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Official documentation: Software manual or vendor release notes. This article is part of a staged content batch; confirm the interface and output in the stated software before public deployment.