06_Error and Bias Overview

Question 1

Error is the difference between_______?

Answer 1

_ the recorded value of a measurement (i.e., from the sample) and the true value of a measurement (i.e., from the entire population).

Example: In a population of 100 people, 20 are college students. If we select a sample of 5 people, how many would be expect to be college students?
20/100 = 1/5àsample should have 1 college student

Question 2

What is the difference between Random vs. Systematic Error?

Answer 2

• Random Error = chance error, variability, variance, random variation, “noise”
• Random error is due to chance Systematic Error = BIAS, constant error Systematic error is not due to chance alone

Question 3

Random Error?

Answer 3

green - the distribution of x with random error
blue- the distribution of x with no random error
- random error does not effect the average, only the variability around the average- goes down if there is an increase study size (sample)

Question 4

Systematic Error (Bias)

Answer 4

• the systematic impact accuracy
• does affects the average - we call a bias
• constant error despite sample size

Question 5

What is the difference between Random vs. Systematic Random vs. Systematic Error (Bias)?

Answer 5

Random Error Solution -
- Perform a sample size analysis before the study begins.
Replicate the study.

Systematic Error Solution-
 - Implement adequate bias control measures before the study begins.
○ Selection bias
○ Measurement bias
○ Participant Bias
○ Experimenter Bias

Question 6

Random error can never be completely eliminated. But it can be reduced —

Answer 6

by increasing the sample size.

Question 7

Sampling error occurs

Answer 7

by chance and is a not a mistake