Midterm 1 - Lecture 5

Question 1

Sources of Variability Affecting Participants’ Scores on the DV

Answer 1

Conceptual independent variable + Error (can break into two components..) = DIFFERENT scores on the IV

Furthermore:

Conceptual independent variable + Random Error + Systematic Error = DIFFERENT scores on the IV

Error: sources of variability in your measure (DV) caused by things other than your conceptual independent variable

Question 2

We can measure and separate systematic error only with…

Answer 2

repeated measures designs

Question 3

Random error:

Answer 3

• Misreading/misunderstanding questions
• Time of day
• Recording error (e.g., wrong bubble in scantron)
• Threatens reliability

Question 4

Systematic Error:

Answer 4

• “systematically decrease or increase scores on DV”
• Ps’ Response biases (eg upper vs lower scale end)
• Individual differences (E.g. Reaction time -generally fast or slow
• Threatens construct validity

Question 5

The more random variability in DV, the harder it is to…

Answer 5

detect the effects/attributes of the IV

• Separating out (i.e. controlling or removing)variability from systematic error allows the impact of the IV to be more obvious.

Question 6

What causes participants’ scored on the DV to differ from each other? (3 reasons)

Answer 6

• Causes:
  a. IV (if there’s an effect)
  b. Random error
  c. Systematic error

Question 7

More variability =

Answer 7

= more overlap between DV for condition 1 vs. condition 2

• harder to see differences due to IV (assuming there is an effect)

Question 8

Less variability (removed math ability)

Answer 8

= less overlap
easier to see differences due to IV

Question 9

Benefits of Repeated Measures Designs:

Answer 9

• Can help us identify the effect of the IV on the DV

○ Identifies some of the random error variability in the DV scores to be systematic
○ Remove systemic error from ratio
○ Means we can use fewer participants