Study announcement if you are interested!
Questions
 Is there one type of mixed design that is more common
than the other types?
 Even though there are a lot more participants in a between
subjects factorial design than within subjects, does this
complexity lead researchers to be more apt to using within
subjects rather than between subjects?
 Is there a maximum number of factors or is it limitless if you
can make a study around them?
 How would you draw 2x2x4 experiment?
 If a variable causes increased variance should you make
that variable a factor?
 If you have a 3-factor study do all three lines have to cross
to indicate an interaction between the factors?
More Questions
 What is the significance of an interaction in a given
study that uses a factorial design?
 Is it always necessary to use statistics in an
experiment?
 On the upcoming exam, can you please provide a
list of key terms for us to reference so that we can
focus on understanding their meaning and
application rather than vocabulary lists?
 Is there a way to know our grades before the final?
 For the extra credit paper can it be a critique about
a topic we discussed in class?
Descriptive and Correlational
Research Strategies
Chapters 12 and 13
Dusana Rybarova
Psyc 290B
May 31 2006
Outline:
1.
2.
3.
4.
Observational research design
Survey research design
Case study design
Correlational research strategy
Introduction
 both the descriptive and correlational strategies are
nonexperimental approaches to research
 no attempt to manipulate or control or interfere with the
variables
 descriptive strategy
– measures a variable(s) as they exist naturally
– the goal is to describe the variable(s)
– three descriptive research designs will be considered
 observational research, survey research, case study research
 correlational strategy
– measures two or more variables as they exist naturally
– the goal is to establish that a relationship exists between
variables
1. Observational research design
 in the observational research design the
researcher observes and systematically records
the behavior of individuals in a order to describe
the behavior
 naturalistic observation
– a researcher observes behavior in a natural setting as
unobtrusively as possible
– e.g. observing the behavior of children in a classroom
– (+) behavior is observed in the real world
– (-) time consuming, potential for observer influence
1. Observational research design
 participant observation
– the researcher engages in the same activities
as the people being observed, in order to
observe and record their behavior
– e.g. gang meeting or treatment of mental
patients
– (+) get info not accessible otherwise
– (-) time consuming, can be dangerous
1. Observational research design
 contrived observation
– observation of behavior in settings arranged
specifically for observing and recording of
behavior
– e.g. parent-child interactions
– (+) don’t have to wait for the behavior to occur
– (-) less natural
2. Survey research designs
 a research study that uses a survey to obtain a
description of a particular group of individuals is
called a survey research design (only describing)
 e.g. customer surveys, eating behavior surveys
etc.
 constructing a survey
– e.g. demographic questions at the end of survey,
sensitive questions in the middle of the survey,
appropriate vocabulary
2. Survey research designs
 three types of questions:
 open-ended questions
– e.g. What do you think about environmental pollution?
– advantages (flexibility)
– limits (different interpretations of questions, different
format and length of answers, difficult to quantify)
 restricted questions
– you present the participant with a limited number of
response alternatives (e.g. multiple choice questions)
– advantages (easy to quantify and analyze)
– limits (less flexible than open-ended questions)
2. Survey research designs
 Self-report measures (cont.)
– types of questions (cont.)
 rating scale questions
– require a participant to respond by selecting a numerical
value on a predetermined scale
– participants have the tendency to avoid the two extreme
categories (actual scale is reduced by 2 categories)
– participants tend to answer all of the questions in the same
way (this is called response set)
– semantic differential (presents a list of adjectives, e.g.
honest, and asks participants to use the scale to rate how
well each adjective describes a particular individual (not
descriptive describes perfectly))
2. Survey research designs
 selecting relevant and representative participants
– e.g. specific groups
 administering a survey
– mail surveys
 convenient and nonthreatening but response rates are low
– phone surveys
 can be conducted from home but time consuming
– in-person surveys
 100% response rate but time consuming with individual
interviews
3. Case study design
 involves the in-depth study and detailed
description of a single individual
 may involve an intervention or treatment
administered by the researcher
 when a study does not include any treatment or
intervention, it is often called a case history
 e.g. Eve White (multiple personality disorder) or
neuropsychological patients (H.M.)
3. Case study design
 strengths
–
–
–
–
–
not averaged over a diverse group
detailed description
vivid, convincing
can study rare and unusual events
can identify exceptions to the rule
 weaknesses
– limited generalizations
– potential for selective bias
– potential for subjective interpretations
4. Correlational research strategy
 two variables are measured and recorded for each
individual
 the measurements are then reviewed to identify
any patterns of relationship that exist between the
two variables and to measure the strength of the
relationship
 can be used for making predictions
– first variable is called predictor variable (e.g. GRE
score)
– second variable is called criterion variable (e.g.
academic performance)
4. Correlational research strategy
 Positive relationship
– There is a tendency for two variables to change
in the same direction; as one variable
increases, the other also tends to increase.
 Negative relationship
– There is a tendency for two variables to change
in opposite directions; increases in one variable
tend to be accompanied by decreases in the
other.
4. Correlational research strategy
positive correlation
negative correlation
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positive
correlation
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negative
correlation
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4. Correlational research strategy
 Applications of the correlational strategy
– Prediction
 Predictor variable (e.g. GPA)
 Criterion variable to be predicted (e.g. grad school
success)
– Reliability and validity
 Calculating correlations in test-retest reliability and
concurrent validity
– Evaluating theories
 E.g. Heredity and IQ correlations between twins
4. Correlational research strategy
 strengths
– nonintrusive – natural behaviors
– high external validity
 weaknesses
– cannot assess causality (e.g. TV and
aggressive behavior)
– third-variable problem
– directionality problem
– low internal validity