Non-experimental designs. Outline 1.Experimental vs. non-experimental research 2.Four kinds of non-experimental research: – Observational research – Archival.

Non-experimental designs

Outline

1. Experimental vs. non-experimental research

2. Four kinds of non-experimental research:– Observational research– Archival research– Case studies– Surveys


• Experimental research requires exerting control.

• Experimenters exert control through manipulation and assignment


• Manipulation • researcher systematically varies conditions under which participants perform task

• “treatments”


• Manipulation• Assignment

• researcher decides who gets which treatment

1. Experimental and non-experimental research compared

• Non-experimental research allows researcher much less control

• No assignment• In many cases, no

manipulation


• Four approaches:– Observational

• Recording ongoing behavior without trying to influence it.


• Four approaches:– Observational– Archival

• Testing a hypothesis using data that the researcher did not collect


• Four approaches:– Observational– Archival– Case study

• Researcher carries out very detailed examination of individual cases

Experimental and non-experimental research compared

• Four approaches:– Observational– Archival– Case study– Survey

• Researcher collects information on beliefs, attitudes, preferences, behaviors, and their correlations.

Observational Research

• The researcher observes behavior without influencing it.

• Goals:

– to describe behavior as it naturally occurs


• The researcher observes behavior without influencing it.

• Goals:

– to describe behavior as it naturally occurs– to assess relationships among variables present


• Four approaches to non-experimental research:– Observational– Archival– Case study– Survey

• Four approaches to observation:

i. Naturalistic observationii.Participant-observer

researchiii.Structured observationiv.Field experiments

Observational Archival Case Study Survey

NaturalisticParticipant-

observerStructuredobservation

Fieldexperiments

Naturalistic Observation• Observing phenomena that

cannot be created in lab, for practical or ethical reasons

• Effects can be observed when such events occur naturally

Naturalistic Observation• Physical trace measures

– e.g., how “well-thumbed” is a book? – Where do paths through the snow go?

• Reactivity– subjects react to the presence of the observer

Naturalistic Observation

• Example: effect of early childhood isolation on later psychological development.

• We can’t isolate children to study them

• But we can use naturalistic observation when we discover such cases

Naturalistic observation• Candland (1993) –

descriptions of feral children (raised outside human cultures)

• Curtiss (1977) case studies of children subjected to unusual isolation by parents (e.g., Genie)

• Spitz (1965) – observation of institutionalized children– Showed effects of deprivation

of stimulation during infancy and early childhood





Participant-observer research

• Observer joins a group for the purpose of studying group members

• Undisguised vs. disguised

• Why use disguised observation?– Access to behavior and situations

Participant-observer research

• Observer joins a group for the purpose of studying group members

• Potential cost to objectivity– Stockholm syndrome





Structured observation

• Researcher exerts some control

– Eleanor Gibson’s visual cliff studies

– Piaget’s studies

• Replication depends upon following exactly the same procedures





Field experiments

• Researcher manipulates one or more variables in a natural setting to determine effect on behavior

• One end of the intervention – non-intervention continuum

Field experiments example

• Crusco & Wetzel (1984)

• effect of touching on restaurant customers

• waitresses worked as confederates

• tip amount was dependent variable

Field experiments example

• Crusco & Wetzel (1984)• Compared No Touch

condition with Fleeting Touch and Shoulder Touch conditions

• Men tipped more than women

• Both men and women tipped more after being touched at some point during their meal.


• Four approaches to non-experimental research:– Observational– Archival– Case study– Survey

• Testing a hypothesis using data that the researcher did not collect

b. Archival Research

• Archival records are a rich source of data– No possibility of reactivity– Often very inexpensive

approach

• Government files• Corporations• Universities• Newspapers• Google cache• Internet wayback machine

b. Archival Research – an example

• Lau & Russell (1980)

– Tested external validity of laboratory findings on causal attributions

• People make internal attributions for success and external attributions for failure

Lau & Russell (1980)

• Sports pages in 8 daily newspapers

• Found 594 explanations for success and failure involving 33 sports events

• Proportions of internal attributions:

• success – 75%• failure – 45%

Case Studies

• Intensive studies of individual cases.– Strength: you learn a lot about the case studied– Weakness: results may not generalize

• We’ll come back to this topic when we look at Single-Subject Experiments.

Surveys - Definition

• A procedure for systematically collecting data on attitudes, preferences, knowledge, or behavior by asking people questions.

• The answers provide information about the group(s) that those people represent.

d. Surveys

• Use surveys when:– You want data regarding a large group of people (a population)– Measuring whole population is too expensive in time, money or other resources

• Population = all the cases of interest

Surveys

• We’ll look at surveys in greater detail in the next lecture…

Non-experimental designs. Outline 1.Experimental vs. non-experimental research 2.Four kinds of non-experimental research: – Observational research – Archival.

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Non-experimental designs. Outline 1.Experimental vs. non-experimental research 2.Four kinds of non-experimental research: – Observational research – Archival.