Nonexperimental designs Outline 1 Experimental vs nonexperimental research

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

Observational Naturalistic Archival Participantobserver Case Study Structured observation Survey 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 – nonintervention 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 nonexperimental 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…