Chapter 12 Quasi-Experimental, Correlational, and Naturalistic Observational Designs @ 2012 Wadsworth, Cengage Learning

Chapter 12Chapter 12

Quasi-Experimental, Quasi-Experimental, Correlational, and Correlational, and

Naturalistic Naturalistic Observational Observational

DesignsDesigns@ 2012 Wadsworth, Cengage Learning

@ 2012 Wadsworth, Cengage Learning

Topics

1. Closed and Open Systems2. Quasi-Experimental Designs3. Correlational Procedures4. Naturalistic Observations


Closed and Open Systems


Closed and Open Systems

• Closed system: one in which the important factors that influence the environment are controlled by the experimenter

• External validity: generalizability of an experimental outcome

• Open system: one in which the participants are influenced by a number of factors over which experimenters have little control


Closed and Open Systems (cont’d.)

Figure 12.1 Number of assaults reported in San Francisco before and after the 1989 Loma Prieta earthquake

Source: Pennebaker (1991).



Figure 12.2 Percentage of individuals reporting conflict after the 1989 Loma Prieta earthquake




Figure 12.3 Percentage of individuals reporting dreams about the 1989 Loma Prieta earthquake and the 1991 Persian Gulf War




• Quasi-experimental designs: often used to evaluate the impact of some variable on an ongoing process

• Correlational designs: attempt to describe the relationship between two variables

• Naturalistic observation techniques: describe an ongoing process in its natural setting


Quasi-Experimental Designs


Quasi-Experimental Designs

• Time series design– Within-subjects design– Useful when we are interested in the effects of an

event that has happened to all members of the population that we are studying

• Single-group pretest-posttest design: involves comparing a single pretest measure with a single post-test measure


Figure 12.6 Hypothetical results of a single-group pretest-posttest design studying the effects of relaxation exercises on (a) the total points scored by a gymnastics team and (b) the coach’s estimate of the gymnasts’ composure


Quasi-Experimental Designs (cont’d.)

• Interrupted time series design: involves making several pretest and several posttest measurements

Figure 12.7 Interrupted time series design. In this figure, O represents each observation or test score and X represents the occurrence of the phenomenon under study. Note that the phenomenon under study, X, interrupts the periodic measurement of our group of subjects (after Campbell & Stanley, 1963)


Figure 12.8 Hypothetical outcomes of an interrupted time series design examining the effects of relaxation exercises on the total points scored by a gymnastics team in 10 weekly meets. X marks the point at which the exercises were introduced. (a) Outcome in which the pretest and posttest scores are fairly consistent. (b) Outcome characterized by much variability in the pretest and posttest scores.



Figure 12.9 Multiple time series design. In the figure, O represents each periodic observation or test score; X represents the occurrence of the phenomenon under study. Note that the phenomenon under study, X, interrupts the periodic measurements of the experimental group but not of the control group (after Campbell & Stanley, 1963)


Figure 12.10 Hypothetical outcomes of a multiple time series design examining the effects of relaxation exercises on the total points scored by a gymnastics team in 10 weekly meets. X marks the point at which the exercises were introduced to the experimental group. (a) Outcome in which the experimental group’s performance improved and the control group’s did not. (b) Outcome in which both groups’ performance temporarily improved



• Nonequivalent before-after design– Used when we want to make comparisons

between two groups that we strongly suspect may differ in important ways even before the experiment begins

– Widely used in educational research


Figure 12.13 Example of a nonequivalent before-after designSource: Adapted from Levitt and Leventhal (1986).

Figure 12.12 Nonequivalent before-after design. In this figure, O1 and O2, respectively, represent the pretreatment and posttreatment dependent measures for each group; X represents the treatment or independent variable. Note that for this design, group comparisons are made between the differences in the scores for each group rather than directly between posttreatment scores (after Campbell & Stanley, 1963)



• Retrospective and ex post facto designs– Attempt to use empirical procedures for

suggesting meaningful relationships between events that have occurred in the past

– Weak forms of inference• However, can be used to good advantage in the testing

of alternative hypotheses (Kerlinger, 1973, 1986)


Correlational Procedures


Correlational Studies

• Describe a relationship between two variables• However, do not attempt to show how one

variable influences the other• Correlation coefficient: statistic commonly

used for establishing a degree of association• A lack of correlation does rule out any

possibility of causality


Naturalistic Observations


Naturalistic Observations

• Simply paying attention and observing• Greatest single application: Darwin’s 5-year

voyage on HMS Beagle– Amass descriptive knowledge about a

phenomenon– Gain insight about general patterns


Concerns While Making Naturalistic Observations

• Reactive behavior: when a participant’s behavior is influenced by the mere presence of the observer

• Undetected observations: unobtrusive observations

• Selective perception: when the observations of untrained observers are markedly influenced by what they expect to see


Concerns While Making Naturalistic Observations (cont’d.)

• Data analysis– Review data several times– Describe the major patterns of behavior– Examine instances of atypical behavior– Evaluate any theoretical ideas you may have

recorded– You may get insights about underlying causal

factors


To Conceal or Not to Conceal; To Participate or Not to Participate• Sometimes there is no reasonable way to

collect data without being seen– Conceal identity as researchers – Become actively involved in the process

• Others make no attempt to conceal• Decision about whether to be an active

participant– Depends on the phenomenon that we are

studying


To Conceal or Not to Conceal (cont’d.)

• Deciding whether to remain concealed or to reveal your identity– Depends on whether you are observing highly

reactive behaviors– If the behavior of your participants will be

different, then use some sort of concealed-observation strategy

– If there is much to be gained by personally experiencing, then consider participating


Naturalistic Observations (cont’d.)

• Advantages– Describe behaviors as it naturally occurs– Studies behavioral processes over a period of time

• Disadvantages– Tend to be qualitative– Representativeness of our sample may be

compromised– Do not provide information about how one

variable influences another


Summary

• Quasi-experimental designs: set of designs that do not have the necessary controls to rule out important threats to internal validity

• Correlational designs: focus on describing a relationship between two variables

• Naturalistic observation: process of observing organisms, usually in their natural environment

Documents

Chapter 12 Quasi-Experimental, Correlational, and Naturalistic Observational Designs @ 2012 Wadsworth, Cengage Learning