Lecture 17Psyc 300A

HW 8: Setting Up a Factorial ANOVA

Serve Other Serve Other Serve Self Serve SelfAlone With Another Alone With Another

5 7 3 55 8 3 65 9 4 66 9 4 76 7 4 66 8 3 56 8 3 65 9 4 65 9 4 75 7 4 6

HW8: SPSS Data File

WhoFor WhoWith Rating(other vs self) (alone vs with another)

1 1 51 1 51 1 6

…….1 2 71 2 8

…….2 1 32 1 3

……2 2 52 2 6

Another SPSS Example

• Hand raising study– Do boys and girls raise their hands in

school at different frequencies?– Do children of different ages raise

their hands at different frequencies?– Does how much a boy or girls raises

their hand depend on their age?

Quasi-Experiments

• May include the following:– No control group– Non-manipulated IV, participant

variable– No random assignment to groups

• Major problem: Confounding• Example:

– An intervention to reduce fear of public speaking

Types of Quasi-Experiments

• Single-Group Posttest-Only Design(Tx group) Tx O

• Single-Group Pretest/Posttest Design

(Tx group) O Tx O

• Single-Group Time Series Design(Tx group) O O O Tx O

O

Types of Quasi-Experiments

• Nonequivalent Control Group Posttest-Only Design (Tx group) Tx O

(Control group) Tx O

• Nonequivalent Control Group Pretest/Posttest Design

(Tx group) O Tx O

(Control group) O No Tx O

Types of Quasi-Experiments

• Multiple-Group Time-Series Design(Tx group) O O O Tx

O O(Cntrl grp) O O O Tx O

O

Threats to Validity

• Selection: Occurs when one group initially differs from another

• Maturation: Participants change over time• Attrition/Mortality: Occurs when participants

drop out• History: Events take place between

measurements that are not related to IV• Instrumentation: Changes may occur in the

measurement device over time (including human measuring devices)

• Testing: Effects of repeated measurement on same person

• Statistical Regression: Arises when participants are selected based on extreme scores

Single-Subject (or Case) Designs

• Advantages– Simple– In a group design, the mean

differences may not represent any particular individual

• Disadvantages– External validity, generalizing results– Work best on IVs which have

reversible effects

Reversal Designs

• ABA reversal design• ABAB reversal design

– This reversal ends with treatment condition

• Example: – Caffeine and my clarity in the classroom

• A=caffeinated coffee, B=decaf

– Coaching and my clarity in the classroom• A=no coaching, B=coaching

Multiple-Baseline Design

• We look at the effect of introducing a treatment across different– Participants

• Ex: Using students’ names to increase class participation in PSYC 300A

– Behaviors• Ex: Using praise to increase cooperation at

home (cleaning room, doing dishes, yard work)

– Situations • Ex: Mom, dad, and caretaker-grandparent use

listening skills sequentially with quiet kid