Simple Random Sampling (SRS) is a basic sampling technique used in statistics where every member of a population has an equal and independent chance of being selected for the sample.
Key Features
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Equal probability: Each individual is equally likely to be chosen.
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Independence: Choosing one unit does not affect the chance of choosing another.
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Unbiased selection: Helps produce samples that represent the population well.
How It Works
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List all members of the population (a sampling frame).
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Assign each member a number.
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Use a random method to select the desired number of units, such as:
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Random number tables
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Computer-generated random numbers
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Lottery-style draw
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Example
A class has 40 students. To randomly choose 5 for a survey:
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Number students 1–40
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Use a random number generator to pick 5 unique numbers
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Those students form the sample
Advantages
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Easy to understand and use
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Low selection bias
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Often provides a representative sample
Disadvantages
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Requires a full list of the population
- Can be inefficient for large or scattered populations
