Chapter 11 - Final

Question 1

Variance Type of Experiments (Differences)

Answer 1

• Within-subject
• Between-subject
• Between-group
• Within-Group

Question 2

Design Type of Experiments

Answer 2

• Between-subject
• Within-subject

Question 3

Within-Subject

Answer 3

• Differences within the same individual (someone is not the same day to day)
  X1a ≠ X1b ≠ X1c ≠ X1d

Question 4

Between-subject

Answer 4

• Differences between people (they are different than others)
  X1 ≠ X2 ≠ X3 ≠ X4

Question 5

Between-group

Answer 5

• Differences across groups (groups that are different)
  M1 - M2 ≠ 0

Question 6

Within-group

Answer 6

• Differences within the same group (individuals making up the group will be different)
  X1 ≠ X2 ≠ X3 ≠ X4…..Z1 ≠ Z2 ≠ Z3 ≠ Z4

Question 7

Between-Subject Group Design

Answer 7

• Different “subjects” in each group
• each measured once
• Hypothesis tested:
  Group 1 average ≠ Group 2 Average

Question 8

Within-Subject Group Design

Answer 8

• Different “subjects” in each group
• each measured twice
• Hypothesis tested:
  Average pair difference ≠ 0

Question 9

Order Effects

Answer 9

1. Practice: get better on the dependent Variable test
2. Fatigue: get tired and bored with the dependent variable.
3. Carryover: effect of an earlier treatment lingers
   Example: A drug given earlier in the day may
   affect performance on a later trial.
4. Sensitisation: Participants figure out the hypothesis near the end of the study.

Question 10

Range Effects

Answer 10

• Best performance near middle of range
• Choose levels that allow generalization to real-world (practical)

Be careful when selecting ranges to be broad enough to catch everything and is practical

Question 11

Approaches to order problem

Answer 11

• Avoid the problem: use between-subject designs instead
• reduce the practice, fatigue, carryover, and sensitization effects (measure only once and use of distractor sets)
• randomize the sequence of treatment
  a.) counterbalance designs (guaranteeing that you
  have just as many with treatment A before B or
  B before A)

Question 12

Reduce Specific Order Effects

Answer 12

• Practice Effects: Before starting the experiment, give participants plenty of practice on the DV task.
• Fatigue Effects: Keep experiments short
• Carryover Effects: space treatment far enough apart
• Sensitization Effects: Don’t let participants know what the DV is

Question 13

Randomize Sequence of Treatments

Answer 13

• Participants get treatments in a random order
  a.) Advantage:
  i. participants won’t all receive the same
  sequences of treatments.
  b.) Disadvantage:
  i. randomization alone doesn’t guarantee that order effects will be balanced out.

Question 14

Counterbalance Designs (2 Factorial ANOVA)

Answer 14

• All participants receive each treatment
• Treatment levels are balanced
• ABBA counterbalancing
  a.) assumes confounding effects are linear (due to order of effects are reversible.)
• treat order Independent variable as between-
  subject variable
  a.) the between-subject factors manipulate the
  order of treatment.

Question 15

Counter Balance Advantages & Disadvantages

Answer 15

Advantages:
Ensures that routine order effects are balanced across conditions; thus, if there are 2 treatments & 10 participants:
* 5 participants will get T1 then T2
* 5 Participants will get T2 then T1

Disadvantages:
Need to use an ANOVA to analyze results and need more participants

Question 16

Results from a 2X2 Counterbalanced Design

Answer 16

• Possible Main Effect of treatment
• Possible Main Effect of counterbalancing
• Possible Treatment X Counterbalacing Interaction

Question 17

How to determine Main Effects or Interaction on Graphs

Answer 17

Main Effects: flat lines and midpoints are separated
Interaction: Lines are not parallel, and mid points are connected.

Question 18

Latin Square

Answer 18

• Allows for counterbalancing using fewer groups. Looks for sequences of treatments so that:
  a.) every treatment precedes and follows every
  other treatment the same number of times
  b.) and each position in the sequence

Nice for even numbers only; odd numbers produce a mirror of the square, producing 6 unique conditions

Example: 4 treatments A,B,C,D (4 X 3 X 2 X 1)
There are 24 possible combinations; using the Latin square, we can reduce them to 4.

Question 19

Matched Pair Designs (combined with within-subjects and between-subjects)

Answer 19

1. Matched up similar participants that correlate with the DV
2. Use random assignment to put one member of each pair in the treatment group(s), the other in the control group(s)

Only effective if matching is appropriate for DV

Question 20

Match Pair Designs Info

Answer 20

1. Matched “subjects” in each group
   a. each measured once
   b. Hypothesis tested:
   Average pair difference ≠ 0
   Example: Yolk Control Design (kitten brought up in an environment of only vertical lines and later only associated everything with vertical lines.)
2. How to match:
   a. should correlate strongly with DV
   i. use the DV
   ii. previous research
   b. If the matching variable is unrelated to the DV
   i. matching will not reduce the random error
   ii. matched designs have half the df (degrees of freedom) of between-subjects design
   iii. lower df (degrees of freedom), higher t (or F, or…) needed for significance

Question 21

Single Variable Experiments

Answer 21

• Advantages:
  a.) determine if there is an effect
  b.) easy to analyze and interpret
  c.) rule out competing theories
• Disadvantages
  a.) no ability to determine the shape of the
  function (only if you have more than 2 dots on a graph)
  b.) limits Interpolation (w/in known boundaries) and Extrapolation (outside of known
  boundaries)

Question 22

Multilevel Experiments

Answer 22

• 1 IV with more than 2 groups

Advantages:
a.) better able to tell the shape of the function
b.) common in behavioral and drug research
Disadvantages:
a.) requires more time and effort
b.) harder to analyze and interpret the results

Question 23

Factorial Design

Answer 23

• Factors can be within or between-subjects
• Mixed factorial designs

Advantages:
a.) Interactives
b.) make random variables into factors
c.) decreases error variances
Disadvantages:
a.) more effect
b.) each additional factor increases the number of
cells

Question 24

Choosing Designs

Answer 24

• Between-subjects:
  a.) if sensitization, practice, fatigue
  i. have enough participants
  ii. want to generalize, and in real life, people are
  exposed to only one level of the treatment
• Within-subjects:
  a.) if sensitization, practice, fatigue, or carryover
  effects are not likely
  i. want a powerful design
  ii. hard to find participants
  iii. want to generate, and in real life, people are
  exposed to both treatments
• Matched Pair:
  a.) easy to obtain scores on matching variable
  b.) matching variable correlates highly with DV
  c.) hard to find participants

Question 25

2 X 2 Counterbalanced Design
(within-subject design and want to balance out)

Answer 25

*want to balance order effects
* interested in the nature of order effects (if treatment has an effect)
* have enough participants
* no concern of hypothesis guessing

Question 26

Factorial Design

Answer 26

• you want to look at more than 1 IV
• you want to know about interactions
• have enough participants
• appropriate concerns depending on each factor (between or within)