Selecting a Sample

Master different sampling techniques and methods. Grade 9 Alberta mathematics.

Lesson 9.4 of Probability & Statistics in Grade 9 Math — Alberta curriculum lessons.

What you'll learn in this lesson

• Selecting a Sample. Learn how to choose a fair and accurate sample from a population using different sampling methods.

Inside the lesson — a free preview

Understanding Populations and Samples

A population is the entire group you want to study.A sample is a smaller group chosen from that population to represent it.

Example:. If you want to know how much time Grade 9 students spend on their phones,

When we can't survey everyone, we use sampling methods to make sure our results are fair and accurate.

Common Sampling Methods

Let's look at the most common ways to select a sample:

1. Simple Random Sampling

2. Systematic (or Interval) Sampling

✨ Tip: This is quick and easy, but make sure the list order doesn't affect your results! ✨

3. Cluster Sampling

✨ Tip: This method saves time when the population is spread out. ✨

4. Self-Selected Sampling

✨ Tip: This method can lead to bias since only certain people choose to respond. ✨

5. Convenience Sampling

✨ Tip: This is fast but not always accurate—it may not represent everyone. ✨

6. Stratified Random Sampling

✨ Tip: This ensures all groups are represented fairly. ✨

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