Plan representative samples using interval and start choices. Check coverage, fraction, and selected units instantly. Export tables and charts with practical survey guidance included.
| Scenario | Population Size | Sample Size | Interval | Random Start | Selected Units |
|---|---|---|---|---|---|
| Household Survey | 40 | 8 | 5.0000 | 3 | 3, 8, 13, 18, 23, 28, 33, 38 |
| Inventory Check | 75 | 12 | 6.2500 | 2 | 2, 9, 15, 21, 27, 34, 40, 46, 52, 59, 65, 71 |
| Student Records | 120 | 15 | 8.0000 | 5 | 5, 13, 21, 29, 37, 45, 53, 61, 69, 77, 85, 93, 101, 109, 117 |
Sampling interval: k = N / n
Sampling fraction: f = n / N
Selection rule: Unit_i = ceil(r + (i - 1) × k)
Wrap rule: If a unit exceeds N, subtract N until it returns to the valid range.
Where: N is population size, n is sample size, k is the interval, and r is the random start.
This calculator follows a practical systematic selection process. It first computes the interval, chooses a valid random start inside the first interval, then advances by one interval for each later draw. If a computed position passes the end of the population, it wraps to the beginning.
Systematic sampling selects units at regular intervals from an ordered population after choosing one random starting point. It is simple, fast, and easy to audit.
The interval equals population size divided by sample size. For example, if N is 100 and n is 10, the interval is 10.
A random start helps avoid always picking the same pattern. It improves fairness and gives every unit in the first interval a chance to begin the sample.
No. Without replacement, sample size must be less than or equal to the population size. This calculator validates that rule before generating results.
The calculator keeps the exact interval and uses cumulative positions with ceiling and wrap logic. That keeps the procedure practical for uneven divisions.
Avoid it when the ordered list contains hidden periodic patterns that match the interval. In that case, the sample may overrepresent or miss repeating groups.
No. Labels are optional. They help map selected unit numbers to names, IDs, codes, or other ordered records when you want a more readable output.
The exports include summary metrics and the selection sequence table. This makes it easier to document sampling choices, share results, and archive project records.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.