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Research Methods Complex Designs. Lecture Outline One-way Designs Factorial Designs Main effects Interactions.

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Presentation on theme: "Research Methods Complex Designs. Lecture Outline One-way Designs Factorial Designs Main effects Interactions."— Presentation transcript:

1 Research Methods Complex Designs

2 Lecture Outline One-way Designs Factorial Designs Main effects Interactions

3 One-Way Designs One-way refers to one independent variable Two groups design The simplest one-way design One IV with 2 levels Foot-in-the-door technique Get person to consent to small task first, then ask for larger task EXAMPLE: Freedman & Fraser (1966) Went door to door Small request: Sign petition Large request: Huge, ugly sign on lawn Experimental group= small then large Control group = large request only

4 Foot-in-the-Door Compliance with Large Request

5 More than two levels… Several reasons you may want more than 2 levels of one IV A) 2 levels cannot provide much information about the exact relationship between IV and DV B) 2 levels cannot detect curvilinear relationships C) May be interested in more than 2 groups

6 A) Lack of Precise Information Motivation and performance on a motor task 2 levels of reward $0 $4 AMOUNT OF REWARD PERFORMANCE

7 A) Lack of Precise Information Increased to five levels Positive monotonic relationship $1$2$3 $0 $4 AMOUNT OF REWARD PERFORMANCE

8 B) Curvilinear relationships Nonmonotonic Increases in the value of one variable are accompanied by increases and decreases in values of another Fear and attitude change. Level 1Level 2Level 3 Low High DEPENDENT VARIABLE

9 C) Interested in More Than Two Things Effects of animal companionship on nursing home residents 2 group design: Dog / No Dog More than 2 groups Dog, Bird, Cat, No animal Stress reducing techniques (Bruning & Frew, 87) 4 group design Exercise, management skills training, medication, control All 3 techniques decreased blood pressure and pulse

10 Increasing the IVs: Factorial Designs Factorial designs More than one independent variable (or factor) Determining the number of conditions 2 x 3 6 conditions 3 x 3 9 conditions 2 x 2 x 2 8 conditions Number of levels of first IV Number of levels of second IV Number of levels of third IV X X

11 A 2 x 2 Design Head movement and persuasive arguments Participants listened to a persuasive argument while moving their head Independent variables Persuasive argument: Tuition increase or tuition decrease Head movement: Nod head or shake head Conditions? 2 x 2 = 4

12 A 2 x 2 Design Tuition decrease- Nodding Tuition increase- Nodding Tuition decrease- Shaking Tuition increase- Shaking Persuasive Argument Movement of Head Nodding Shaking Tuition decreaseTuition increase

13 Main Effects Effect each variable has by itself DV: Willingness to accept increases in tuition Persuasive Argument Head Movement DecreaseIncrease Nodding Shaking485465

14 Main Effect for Head Movement Persuasive Argument Head Movement IncreaseDecreaseOverall means Nodding Shaking

15 Main Effect for Type of Argument Persuasive Argument Head Movement IncreaseDecrease Nodding Shaking Overall means

16 Both Main Effects Persuasive Argument Head Movement IncreaseDecreaseOverall means Nodding Shaking Overall means

17 Interactions The effect of one independent variable depends on the level of the other There is an interaction in the persuasive argument study The effect of the type of argument is different depending on whether the person is nodding or shaking their head Let’s take a closer look

18 Interactions We can look at the data to detect the interaction YUCK!! Persuasive Argument Head Movement DecreaseIncrease Nodding Shaking485465

19 We can look at a line graph Interactions

20 Or we can look at a bar graph

21 Interactions Ordinal (spreading) interaction IV1 has an effect under one condition of IV2 but less of an effect under the other condition of IV2. Disordinal (crossover) interaction There are no main effects of either IV The effects of each IV are opposite at different levels of the other IV

22 Ordinal Interaction IV1 has an effect under one condition of IV2 but less of an effect under the other condition of IV2.

23 Another Ordinal Interaction IV1 has an effect under one condition of IV2 but less of an effect under the other condition of IV2.

24 Disordinal Interaction There are no main effects of the IVs The effects of each IV are opposite at different levels of the other IV Mood during LEARNING

25 Concept Check A professor randomly assigns students to one of four conditions: Learn words in the morning and drink 2 cups of coffee Learn words in the afternoon and drink 2 cups of coffee Learn words in the morning and drink no coffee Learn words in the afternoon and drink no coffee What are the main effects and the interactions in this design? What questions would you ask to evaluate these effects?

26 Concept Check Main effect 1: Coffee factor Are there any differences in students who received coffee compared to those who didn’t? Main effect 2: Time of day factor Are there any differences in students who learned the words in the morning vs afternoon? Interaction: Does the effect of coffee depend on the time of day? Coffee might enhance performance in the morning but impair performance in the afternoon.

27 No main effect of A or B, no interaction Violent TV ThreatA1A2 B120 B220 Provocations - Main Effects & Interactions

28 Main effect of A, no main effect of B and no interaction Violent TV ThreatA1A2 B B Provocations -

29 Main effect of B, no main effect of A and no interaction Violent TV ThreatA1A2 B120 B Provocations -

30 Main effect of A and B, no interaction Violent TV ThreatA1A2 B B Provocations -

31 No main effect of A or B; interaction Violent TV ThreatA1A2 B B Provocations -

32 Main effect of A, no main effect of B; interaction Violent TV ThreatA1A2 B B Provocations

33 Main effect of B, no main effect of A; interaction Violent TV ThreatA1A2 B B Provocations

34 Main effect of A and B; interaction Violent TV ThreatA1A2 B120 B Provocations -

35 Hands on Activities Design Identification Outcomes of Factorial Designs


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