Non-experimental designs

Outline 1.Experimental vs. non-experimental research 2.Four kinds of non-experimental research: – Observational research – Archival research – Case studies – Surveys

1. Experimental vs. non-experimental research Experimental research requires exerting control. Experimenters exert control through manipulation and assignment

1. Experimental vs. non-experimental research Manipulation researcher systematically varies conditions under which participants perform task “treatments”

1. Experimental vs. non-experimental research 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

1. Experimental and non-experimental research compared Four approaches: – Observational Recording ongoing behavior without trying to influence it.

1. Experimental and non-experimental research compared Four approaches: – Observational – Archival Testing a hypothesis using data that the researcher did not collect

1. Experimental and non-experimental research compared 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

Observational Research The researcher observes behavior without influencing it. Goals: – to describe behavior as it naturally occurs – to assess relationships among variables present

Observational Research Four approaches to non- experimental research: – Observational – Archival – Case study – Survey Four approaches to observation: i.Naturalistic observation ii.Participant-observer research iii.Structured observation iv.Field experiments

ObservationalArchivalCase StudySurvey Naturalistic Participant- observer Structured observation Field experiments

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

Observational Research Four approaches to observation: i.Naturalistic observation ii.Participant-observer research iii.Structured observation iv.Field experiments

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

Observational Research Four approaches to observation: i.Naturalistic observation ii.Participant-observer research iii.Structured observation iv.Field experiments

Structured observation Researcher exerts some control – Eleanor Gibson’s visual cliff studies – Piaget’s studies Replication depends upon following exactly the same procedures

Observational Research Four approaches to observation: i.Naturalistic observation ii.Participant-observer research iii.Structured observation iv.Field experiments

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.

Observational Research 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…