1 of 15

Sampling Methods and Bias

2 of 15

Agenda

We’re Doing What Today?

1

3 of 15

Agenda

  • Population vs Sample
  • Sampling Methods
  • Bias
  • Desmos San Antonio

3

4 of 15

Population vs Sample

It’s Obvious But…

2

5 of 15

Population vs Sample

  • The population is the entire dataset of interest (city, species, country, classroom)
  • The sample is the subset of the dataset of interest
    • Typically based on what can be measured
    • Introduces bias since we lose information

5

6 of 15

Bias

This is the sound of inevitability

3

7 of 15

Bias

  • As soon as you measure a subset of a population, bias occurs
    • THIS IS UNAVOIDABLE
  • Sometimes you can anticipate bias
  • When measuring, you try and minimize bias using different sampling methods
  • Bias is the emphasis of one subset over another in the sampling measurement

7

8 of 15

Sampling Methods

Minimize the Bias

4

9 of 15

Sampling Methods

  • Convenience Sampling
    • Whatever sample is easiest to measure (cost, effort, time)
  • Simple Random Sampling
    • Generate a complete list of the population
    • Measure samples randomly from this set

9

10 of 15

Sampling Methods

  • Systematic Sampling
    • Fixed intervals of the population
    • Every 10th person encountered
  • Stratified Sampling
    • Group population into strata
    • Strata are based on shared characteristics
    • Sample from within each strata

10

11 of 15

Sampling Methods

  • Quota Sampling
    • Like Stratified Sampling
    • But sample from each strata based on proportion of entire population

11

12 of 15

Desmos Activity

Seeing Sampling in Action

5

13 of 15

Desmos Activity

  • San Antonio Population

13

14 of 15

Credits

Special thanks to all the people who made and released these awesome resources for free:

  • Presentation template by SlidesCarnival
  • Photographs by Unsplash

14

15 of 15

Presentation design

This presentation uses the following typographies:

  • Titles: Amatic SC
  • Body copy: Encode Sans Semicondensed

Download for free at:�https://fonts.google.com/specimen/Amatic+SC

https://fonts.google.com/specimen/Encode+Sans+Semi+Condensed

​

15

You don’t need to keep this slide in your presentation. It’s only here to serve you as a design guide if you need to create new slides or download the fonts to edit the presentation in PowerPoint®

​

​