# Census vs. Survey

A

**parameter**is a numerical description of a**population**characteristicA

**statistic**is a numerical description of a**sample**characteristic

Census | Population | Parameter |
---|---|---|

Survey | Sample | Statistic |

# Characteristics of a Well-Designed and Well-Conducted Survey

Representative sample

- Must represent the population that you want to
**draw inference**about

- Must represent the population that you want to
Random sample

Does not introduce bias

# Bias

What is it?

How might it occur?

Wording of the question

Sample technique

Under-coverage: miss a certain group of people

Non-response: someone in your sample choose not to respond

# Random Sampling

Simple Random Sample (SRS)

Random digit table

Calculator

- MATH ➡️ PRB ➡️ randInt(lower, upper, number of numbers)

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- Stratified Random Sampling

Cluster Sample

Systematic Random Sample

Comparison

Example

If you wanted to select a sample of school children and you did this by selecting an SRS of

**classrooms**this would be an example of what type of sampling?- Cluster

If you wanted to select a sample of school children and you did this by randomly selecting 5 children from each

**grade**this would be an example of what type of sampling?- Stratified

# Non-Random Sampling

Convenience Sample

- Selecting those that are easy of convenient

Voluntary Response Sample