experimental design: exam one examples

which type of IRB review?

An anonymous online survey asking adults about their favorite study strategies (e.g., flashcards vs. highlighting).​

exempt

which type of IRB review?

A reaction time experiment where participants respond to visual stimuli on a computer.​

expedited

which type of IRB review?

A study involving exposure therapy for participants with diagnosed phobias (e.g., gradual exposure to spiders in a controlled setting).​

full review

Mill’s Inductive Logic Example:

Rose, Donna, and Martha all order different entrees at dinner, and all get the pie for dessert. All three get food poisoning.​

method of agreement (sufficiency)

Mill’s Inductive Logic Example

Jack plants two fields of tomatoes. He fertilizes only one. The field that received the fertilizer grows. The field which didn’t get the fertilizer doesn’t grow​

method of difference (necessity)

In a study of the effects of problem difficulty (easy or hard) and reward size ($1 or $5 for each solution) on an anagram problem-solving task, what are the independent and dependent variables?​

IV = problem difficulty (easy or hard), reward size ($1 or $5)

DV = # analogue problems solved

*2×2 Factorial Design

What are extraneous variables and what happens if they are not controlled properly?​

• factors other than IV that could impact exp results 

• If not controlled, they can introduce noise, create systematic differences between groups, and mask or exaggerate effects, leading to flawed conclusions and a lack of internal validity

Draw a diagram that illustrates the between-subjects design​

(reference image)

Draw a diagram that illustrates the within-subjects design​

(reference image)

which type of study?

IV = type of social skills training (*matching variable autism quotient)

1. direct teaching 

2. play activities 

DV = social interaction observation code 

between-subject, single-factor, two-levels: matched groups 

which type of design?

IV = whether or not TBI occurred

• experimental group: TBI

• control group: no TBI

DV = ability to detect insincerity in others

between-subject, single-factor, two-levels: ex post facto

which type manipulated IV?

A helping behavior study: the effect of the number of bystanders on the chances of help​

situational

which type of manipulated IV?

study of reasoning: give ppl different kinds of logic probs to determine kinds of errors ppl make

task

which type manipulated IV?

memory task on how to memorize list 1) form visual images of the words 2) form associations between adjacent pairs of words 3) repeat each word three times as its presented

instructional

construct a table based on this data:

A memory study with a 2 (type of training) × 2 (presentation rate) factorial, like the example used a moment ago, has these results (DV = words recalled):​

Imagery/2‐sec rate = 20 words​

Imagery/4‐sec rate = 20 words​

Rote/2‐sec rate = 12 words​

Rote/4‐sec rate = 12 words​

what is the main effect? interaction effect?

main effect:

• training type: there is a ME

  • avg words recalled for imagery was 20

  • avg words recalled for rote was 12

• presentation rate: no ME

  • avg words recalled for both 2 sec and 4 sec was 16

construct a graph based on this data:

A memory study with a 2 (type of training) × 2 (presentation rate) factorial, like the example used a moment ago, has these results (DV = words recalled):​

Imagery/2‐sec rate = 20 words​

Imagery/4‐sec rate = 20 words​

Rote/2‐sec rate = 12 words​

Rote/4‐sec rate = 12 words​

graph this data:

• IVs: 

1. laboratory self‐discovery course vs straight lecture course​

2. Students from different majors: Science vs Humanities​

• DV: Score from 1 to 100 on a standardized test of knowledge of General Psychology ​

Score Results:

lab emphasis, science major: 80

lab emphasis, humanities major: 70

lecture emphasis, science major: 70

lecture emphasis, humanities major: 80

Interaction effect?

construct a table for this data:

• IVs: 

1. laboratory self‐discovery course vs straight lecture course​

2. Students from different majors: Science vs Humanities​

• DV: Score from 1 to 100 on a standardized test of knowledge of General Psychology ​

Score Results:

lab emphasis, science major: 80

lab emphasis, humanities major: 70

lecture emphasis, science major: 70

lecture emphasis, humanities major: 80

what is the main effect?

• major

  • no ME

  • both avgs were 75

• learning style “emphasis”

  • no ME

  • both avgs were 75

graph w/ no interaction present?

parallel lines

graph w/ interaction present?

non-parallel lines

6 assumptions when analyzing factorial designs

• #1: Dependent variable at the continuous level (i.e., they are interval or ratio variables, Called Scale in SPSS)​

• #2: Independent variables categorical​

• #3: Independence of observations​

• #4: No significant outliers. ​

• #5: Dependent variable approximately normally distributed (Shapiro-Wilk test for normality)​

• #6: Homogeneity of variances (Levene’s test)​

what type of study is this?

• IV-Manipulated type of note-taking: ​
  1) Laptop note-taking; ​
  2) Handwritten note-taking​

• DV: performance on memory test ​

single-factor, between subject, two level design

what type of study is this?

• IV-Type of social skills training: ​
  1) Direct teaching; ​
  2) Play activities​

• DV: Social Interaction Observation Code​

single-factor, between subject, two level design

what type of study is this?

• IV-Whether or not traumatic brain injury (TBI) had occurred: ​
  1) Experimental group: had experienced TBI​

2) Control group: no TBI​

• DV: Ability to detect insincerity others ​

single-factor, between subject, two level design

ex post facto

what type of study is this?

• IV-Whether or not the color of print and word match: ​
  1) Match​

2) Mismatch​

• DV: Speed and accuracy​

single-factor, within-subjects, two level design

*stroop effect

Bradford + Johnson’s 1972 study:

• One IV, three levels, independent groups​

  • No context (no topic presented)​

  • Context before (topic presented before reading paragraph)​

  • Context after (topic presented after reading paragraph) ​

• DV: recall of paragraph’s ideas​

what type of study is this?

single factor, between-subject, multilevel design

what type of study is this?

• IV = Heart rate training program​

• DV = Resting heart rate​

• Resting Heart Rate 1 Month Before Training Program​

• Resting Heart Rate 1 Month during Training Program​

• Resting Heart Rate 1 Month After Training Program​

single-factor, within-subject, multilevel design