APPENDIX 2.1.A. SIMPLE RANDOM SAMPLING

A procedure for selecting n units out of the N possible units so that all possible samples have an

equal chance of being selected

Process:

1. Number the units of the target population from 1 to N

2. Randomly select n units of the target population

These n units comprise the simple random sample

Example

Objective: Determine the average dissolved oxygen concentration (over an annual period) in the

releases from a flood control project.

Target population: 365 days

Sample size: 52

Simple random sample: Select 52 random numbers between 1 and 365

Random sampling assures the independence of the observations

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