Measurement Errors

Question 1

What is total variance?

Answer 1

SD squared

Question 2

What two categories can you split total variance into?

Answer 2

Systematic and Error Variance

Question 3

What is systematic error?

Answer 3

any variable causing a consistent shift in the mean in a given direction

Question 4

What is Random Error?

Answer 4

Fluctuation in scores due to chance

Question 5

What do different R or R squared values indicate?

Answer 5

Closer to 1 means stronger correlation or less error, closer to 0 means weaker correlation or more error

Question 6

What does a Bland Altman plot show?

Answer 6

Difference against Mean

Question 7

What are the 3 points of visual assessment in a bland altman plot?

Answer 7

• Rand Error: Points deviating from the mean line
• Sys Error: Points evenly distributed about the zero line
• Nature of Error: Consistent left-right

Question 8

How do researchers increase the proportion of variance in total variance?

Answer 8

• Reducing Syst/Rand Error by controlling extraneous variables
• Increasing effect of independent variable

Question 9

How do you consider the smallest worthwhie effect of an intervention in (for example) improving race times against an opponent?

Answer 9

The decrease in the race time as a result of the intervention will need to be below the opponents time by more than his/her error variance