Lecture 3 – Chapter 3 The Starting Point

Science/Research Terminology Variables Variable: Any measurable aspect of behavior or influence on behavior that may change Or… things you manipulate and things you measure Independent Variable: IV Dependent Variable: DV

Independent Variable: Normally (true experiment), it is the variable that you manipulate ANY VARIABLE THAT DEFINES SEPARATE GROUPS …”I” do the research…it’s what “I” manipulate

Either give some subjects 100mg of a drug or give them 25mg or placebo Here the IV is DRUG (varying doses) So, by randomly assigning them to a drug dose you are creating the groups (conditions) of the experiment 100 mg 25 mg Sugar pill IV

Either give some subjects 20, 60 or 40 watts and test their performance on a math test 60 watts 20 watts 100 watts Then vary the type of math test: algebra, geometry

Independent Variable: Normally (true experiment), it is the variable that you manipulate…but in a quasi-experiment not really manipulated the IV is the preexisting condition that the subjects brings into the experiment (also called the “subject” or “classification” variable) ex: sex, age, ethnicity

IV: Levels In general, the number of levels of an independent variable is the number of experimental conditions

Dependent Variable: In either True experiment, Quasi-experiment, or Correlational research: The variable that you hypothesize to have a relationship with the IV..that you expect to be affected by the IV The variable that you measure The response of your subject

Dependent Variable: Reaction time cancer cells errors on memory test

Naturalistic Observation – Low constraint  The observation of subjects in their natural environment  The researcher imposes no limits or changes in the environment or behavior of the subjects No manipulation No IV DV? Behavior? “Variable of interest”

Case Study – Low constraint  The subject is in a moderately limiting environment  The researcher intervenes only slightly  An in-depth description of one subject, organization or event ex: medical field: Case of H.M. No manipulation No IV DV? Behavior? “Variable of interest”

Correlational research – Constraint  Quantify the degree of relationship between two variable  Measurement procedure must be carefully defined and precisely followed  No manipulation of variables – two sets of measurements in the same subject then correlate IV? Grouping variable DV? response

Experimental Research – highest constraint “True Experiment” ex: want to investigate the effects of a drug on depression This should be easy now! IV? Grouping variable DV? response

One last Variable – Not a good thing Extraneous Variable Extraneous: coming from outside, foreign, not permanent, irrelevant Any variable or factor not controlled for by the experimenter that might affect the DV Threat to validity of experiment Internal Validity: are we testing what we set out to test? Methodological soundness of experiment

testing subjects on a memory test …temperature in the room is HOT …impact on the tests results Examining the effects of alcohol on driving and obeying posted signs…but you don’t assess their vision examples of extraneous variables

Experimental Research – highest constraint “True Experiment” Control: Systematic methods reduce threats to validity Extraneous variables (confounds)  without bias assign Subs to groups  RANDOM ASSIGNMENT  the setting is ALL about control  measurement procedures carefully designed and precisely followed

Research Ethics Human Subjects Institutional Review Board (HSIRB) - Consists of members of community & peers - Review research proposals – Yea or Nay - Assure that project meets ethical standards (set by APA. NIH & institution) Informed Consent: a form that provides the subject with enough info to make an “informed” decision

Institutional Care and Use of Animal Committee (IACUC) Research Ethics Veterinarian, non scientist, scientist/researcher Housing, care & use