Edexcel IAL - Statistics 3- 2.1 Simple Random Sampling and Random Numbers- Study notes  - New syllabus

Methods for Collecting Data

In statistics, data are collected in order to investigate questions, identify patterns, and make informed conclusions. The method used to collect data affects how reliable and unbiased the results are.

Types of Data Collection

Common methods of collecting data include:

Surveys and questionnaires – asking individuals for information

Experiments – collecting data under controlled conditions

Observational studies – observing subjects without interference

To draw valid conclusions, the data collected should be based on a representative sample of the population.

Population and Sample

Population: the complete set of individuals or items of interest.

Sample: a subset of the population used to make inferences about the population.

A well-chosen sample should be unbiased and representative of the population.

Simple Random Sampling

A simple random sample is one in which every member of the population has an equal chance of being selected.

Key features of simple random sampling:

• Each individual has the same probability of selection
• Selections are made without bias
• Random numbers are commonly used

Use of Random Numbers for Sampling

To select a simple random sample using random numbers:

• Assign each member of the population a unique number
• Use a table of random numbers or a calculator to generate random digits
• Select individuals corresponding to those numbers
• Ignore numbers outside the required range or repeated selections

This method ensures fairness and reduces selection bias.