Questions

1. Questions • In a correlation research paper do the authors note the predictive variable and the criterion variable? • Is it common to combine different research strategies in a single experiment? • Do researchers sometimes make larger scales for rating scale questions to produce a larger range of responses in order to attempt to avoid the scale being reduced? • Does the type of survey determine what type of question to ask, or is one question better to use than another?

2. More Questions • How valid are correlational studies when there is always a directionality and third-variable problem that can affect the results? • In what sub-field(s) of psychology are case study designs most likely to be used? • For the exercises from Ch11 on factorial designs, I was confused on how to look at a chart/table or a graph and see if there is an interaction. Problems #8 and #9 were very confusing for me.

3. Exam concepts Experiment, third-variable problem, directionality problem, manipulation and control of variables, treatment conditions, levels, ways of controlling extraneous variables (holding constant, matching and randomization), experimental and control groups (no-treatment, placebo), simulation and field studies

4. Exam concepts • between-subjects design (what it is, major adv and disadv), at least two examples of threats to internal validity of btw-subjects designs • Within-subjects designs (what it is, major adv and disadv - time-related, order), dealing with time-related threads and order effects, matched-subjects designs (controlling time and counterbalancing)

5. Exam concepts • Distinction btw nonexperimental and quasi-experimental research strategy, nonequivalent group (general understanding and one example of design), pre-post designs (general understanding and one example of design), developmental research designs (cross-sectional and longitudinal – differences), cohort effects

6. Exam concepts • Factor, factorial design, main effect, interaction, between and within-subjects factorial designs (calculating number of participants and deciphering the notation e.g. 2x3x2), mixed designs • Types of designs under descriptive research strategy (observational, survey, case study), types of observation, types of questions, correlation, positive and negative correlation, predictor and criterion variable, applications of correlations and problems

7. Exam concepts • Differences between case study and single-case design, baseline phase, treatment phase, visual inspection of data, provide example of one specific type of a single-subject design (e.g. ABAB), general adv and disadv of single-subject designs

8. Single-Subject Research Designs Chapter 13 Dusana Rybarova Psyc 290B June 1 2006

9. Outline: • Introduction to single-subject designs • Phases and phase changes • The ABAB reversal design • Dismantling or component-analysis design • Multiple-baseline designs • Strengths and weaknesses of single-subject designs

10. 1. Introduction to single-subject designs • single-subject designs or single-case design are research designs that use the results from single participant or subject to establish the existence of cause-and-effect relationships • Whereas case studies belong to the group of descriptive research strategies, single-case studies are experimental • like time-series research, the single-subject approach typically involves a series of observations made over time but again single-subject designs are experimental and time-series designs are quasi-experimental

11. 1. Introduction to single-subject designs • Evaluating the results from a single-subject study • the presentation and interpretation of results form a single-subject experiment are based on a simple graph of the data • because the results of a single-subject study do not involve any traditional statistical methods, researchers must rely on the visual inspection of a graph to convey the meaning of their results

12. 2. Phases and phase changes • a phase is a series of observations of the same individual under the same conditions • when no treatment is being administered, the observations are called baseline observations; a series of baseline observations is called a baseline phase and is identified by the letter A • when a treatment is being administered, the observations are called treatment observations. A series of treatment observations is called a treatment phase and is identified by the letter B.

13. 2. Phases and phase changes • a consistent level occurs when series of measurements are all approximately the same magnitude; in a graph, the series of data points cluster around a horizontal line • a consistent trend occurs when the differences from one measurement to the next are consistently in the same direction and are approximantely of the same magnitude; in a graph the series of the data points cluster around a sloping line

14. 2. Phases and phase changes • the stability of a set of observations refers to the degree to which the observations show a pattern of consistent level or consistent trend; stable data may show minor variations from a perfectly consistent pattern, but the variations should be relatively small and the linear pattern relatively clear

15. 3. The ABAB reversal design • An ABAB design, also known as a reversal design, is a single-subject phase-change design consisting of four phases: a baseline phase, a treatment phase, a return to baseline phase, and a second treatment phase • The goal of the design is to demonstrate that the treatment causes changes in the participant’s behavior

16. 3. The ABAB reversal design • Limitations of the ABAB design • It is not appropriate for evaluating treatments that are expected to have a permanent or long-lasting effect • There is also the ethical question of withdrawing a successful treatment

17. 4. Dismantling or component-analysis design • This design consists of a series of phases in which each phase adds or subtracts one component of a complex treatment to determine how each component contributes to the overall treatment effectiveness • E.g. reward and punishment for biting behavior in an autistic boy BC-B-BC-C-BC BC – combination of the reward and punishment B – reward only C – punishment only

18. When initial baseline phases correspond to separate participants, the design is called a multiple-baseline across subjects Example (left) from Walker, Shippen, Alberto, Houchins and Cihak (2005) 5. Multiple-baseline designs

19. 5. Multiple-baseline designs • Advantages • The major advantage of this design is that it eliminates the need for a reversal or return-to-baseline phase and is therefore well suited for evaluating treatment effects that are permanent or long-lasting • Disadvantages • The results can be compromised by individual differences between participants or between behaviors (e.g. one participant being more responsive to the treatment than another)

20. 6. Strengths and weaknesses of single-subject designs • Advantages • Researcher can establish a cause-and-effect relationship between treatment and behavior using only a single participant • Flexibility – development of the design depends on participant’s responses • Disadvantages • Problem with generalizations since designs use only one participant • Multiple observations can affect participant’s responses • Absence of statistical controls and reliance on visual inspection of the data

21. References • Walker B., Shippen M.E., Alberto P., Houchins, D.E. & Cihak, D.F. (2005). Using the Expressive Writing Program to Improve the Writing Skills of High School Students with Learning Disabilities. Learning Disabilities Research and Practice, 20(3), 175-183.