---------- INTRODUCTION to PSYCHOLOGY RESEARCH DESIGN ----------
---------- SYLLABUS ----------
Dr. John M. Morgan

REQUIRED TEXT:     Experimental Methodology  eighth edition
			by Larry B. Christensen, Allyn and Bacon, 2001
			ISBN #0-205-30832-5
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Chapter 6

Independent Variable = variable that the experimenter changes 
	within a defined range or the variable of interest. 
	Hypothesized cause
	Presence vs Absence – e.g. Experimental group vs Control 	
		group
	Amount – different quantities presented either to different 	
		groups or same participants at different times.
	Type of the Variable, e.g. qualitative different labels to 		
		members of experimental group where as members of 	
		matched control group have none or same label.
	How to induce variation:
		Instructions, if participants listen and interpret them as 	
			intended.
		Event manipulation – different things happen, e.g. drug 	
			levels, surgery, classrooms
		Individual difference – of participants places them in 	
			different groups, e.g. locus of control already in 	
			place =>nonrandom assignment to groups.
	Operationally Define variables – concrete
		If abstract variable, e.g. anger, review literature to 		
		determine past usage and, use the most appropriate, 	
		previously accepted definition.
	Construct Validity – How do we know that the various levels 	
		of the Independent Variable cause the participants to 	
		behave differently and as we expect? -  Euphoria
		a	clear definition
		b	empirical data that I.V. produces outcome, e.g. 	
			levels of food deprivation produce hunger.
			and not another aspect of IV, e.g. nutrition.
Do levels of one or more I.V. INTERACT with each other?  e.g. 
negative reinforcement schedule vs magnitude of punishment  p159
When a response always (continuously) turns off a soft noise, 
participant will continue to respond for a longer time after the 
response no longer turns off the soft noise than if it turns off a loud 
noise	 but, when a response only sometimes (partially) turns off a 
loud noise, the participant will respond for a longer time after the 
response no longer turns off the loud noise than if the noise is soft.
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Dependent Variable = the variable that measures the influence of 
	the independent variable, - indicator of the effect produced by 
	the variation in the independent variable. e.g. Split Brain – 
	Roger Sperry – how to measure the effect of the brain 
	surgery?
Gender of participant may influence response 
If participant committed -> less faking

Experimenter must replicate study =>reliable

Validity:
	DV actually measures the construct of the IV we want 		
		to measure, e.g. IQ scores = intelligence?
	Does DV covary with similar measures of IV?, e.g. other 	
		depression scales
	Does DV not covary with dissimilar behaviors?, e.g. 
depression 		scale not same responses as intelligence or anxiety.

Reducing Participant Error:
a	measure response a second time outside of experiment
b	measure behavior important to participant
c	measure behavior without participant's knowledge in the field
d	imbed key aspects of IV in the midst of other stimuli, e.g. key 
	questionnaire questions.
e	pretest then unexpected retest
f	use a confederate in the testing situation

Reliability of DV: Are you measuring what you want to measure?  
	Consistency or stability

Discrete Variables = whole units or categories
Continuous Variables = form a - both whole and fractional units.

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to consult with me on any matter during my office hours or
any time that is agreeable to you and me.

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Copyright © 2002, Dr. John M. Morgan, All rights reserved - This page last edited Nov 25, 2002
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