Nature of Research Pt 2
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Transcript of Nature of Research Pt 2
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Nature of Nature of ResearchResearch
Pt 2Pt 2
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Definitions:Definitions:
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CONSTRUCT:
• a fabrication of mind, invisible, unmeasurable.
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THEORY:
• built of constructs,
• showing relationships between constructs,
• a systematic view of phenomena to explain and/or predict,
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THEORY:
• a network of related constructs,
• abstract.
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Theory consists of:
1. Definitions, explication of constructs.
2. Operational Definitions.
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Theory consists of:
• what we wish to measure, observe or manipulate.
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Theory consists of:
• criteria: must exhaust the definition of the constructs, must be exclusive (not include additional things).
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Theory consists of:
•Explication of constructs. •Operational Definitions. •What we wish to measure, observe or manipulate. •Criteria
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VARIABLE: Any quality that has
more than one value.
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HYPOTHESIS: Pertaining to the expected relationships among variables.
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• Must be specific expression of expected answer about relationships among variables.
• Interaction of operational definitions, concrete, observable.
HYPOTHESIS
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From testing of the hypothesis one draws inferences which may allow generalization based on the theory.
HYPOTHESIS
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VARIABLES
• can be added to sharpen the prediction, provide more explanation.
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VARIABLES
Independent Variable: cause.
Dependent Variable: effect.(depends on independent variable)
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“If [I.V.] then [D.V.].”
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VARIABLES
Moderator Variable: moderates the effect
of I.V. on the D.V.
More than one variable effects outcome.
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VARIABLES
Mediated Variable: one that intervenes, allows
one variable to act upon another.
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VALIDITY: Internal• experiment is well
controlled, clean.• clearly measures what
is concluded.• clearly tests the
question asked, the target question.
• with no confounding variables
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VALIDITY: External
• artificiality of created situation.
• is the conclusion generalizable outside of experimental situation?
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VALIDITY: External
Ex. Piaget studied his own children.Can this be generalizable?
A problem of Sample Validity.
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VALIDITY: External
Ex. Study of violent tv watching.Experimental Groupwatches 3 hrs. of violent tv.
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VALIDITY: External
Ex. Study of violent tv watching.Experimental Groupwatches 3 hrs. of violent tv.No Control Group.No Choices given.
A problem of Extreme Treatment.
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Measurement
Is behavior observed a typical expression of what is to bemeasured?
Ex. What does “time-on-task” measure?
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CAUSAL RELATIONSHIP
• must show statistical relationship
• must precede event
• must rule out plausible rival hypotheses
(PRH)
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CONTROL GROUP
• Ask, What is it designed to control for?
• Must be equivalent to experimental group.• Function: to rule out Plausible Rival
Hypothesis.
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Threats to Internal Validity
• HistoryIf the study has multiple
phases, there may be an influence by the early
phase on the later phases.
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Threats to Internal Validity
• TestingAll participants must be sensitized to the same
extent.
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Threats to Internal Validity
• MortalityIf dropouts are not
equally distributed (randomly) there may be systematic bias.
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Threats to Internal Validity
• MaturationParticipants would
improve anyway by growing up.
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HAWTHORNE EFFECT:
Effect of attention paid to participants.
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Threats to Internal Validity are less important in correlational studies than in functional studies. (A correlational study does not show causal relationship.)
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Regression Toward the Mean
Performance varies, and over time values will
gravitate to the mean.
Highs become lower, and lows become higher.
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Random Assignment
(Random Selection)Allows for comparability between
experimental group and control group.Each individual has the same chance to
be in either group.Otherwise there may be bias.
(RA)(RS)
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Sampling
Science of choosing representationally fromeach ethnic, racial, age, class, etc., group.Allows validity with only1100 polled of 260 million.
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Precision
Difference between groups_______________________
Difference between individualswithin group
=
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Precision
D B_____
D W
= Probability (p)
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Standard Deviation
Size of variability of distributionof individual differences.
Mean (x) yields some information,not necessarily meaningful.Range tells more of the story.
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Standard Deviation
Shoe Sizes Mean (x)
8 8.5 10 9.5 9.0
11.5 6 12 6.5 9.0
A
B
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Standard Deviation Shoe size Mean Deviation SS Variation Std Dev
(x) (s2) (σ)
11.5 9 2.5 6.25 1.566 9 -3 9 2.2512 9 3 9 2.256.5 9 -2.5 6.25 1.56
2.76 (x)2 /SSN
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Standard Deviation
6 7 8 9 10 11 12
X
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Standard Deviation
6 7 8 9 10 11 12
X
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Standard Deviation
6 7 8 9 10 11 12
X
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Standard Deviation
6 7 8 9 10 11 12
X
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Standard Deviation
6 7 8 9 10 11 12
X
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Statistical Significance
“Significance of difference” or, meaningfulness.
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Statistical Significance
Ex. Grp #1–Individual InstructionGrp #2–Group Instructionn=30 in each group(could be 3000)RA, RS
Grp. #1 does 3 pts. better on posttest.Is that Significant?
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Statistical Significance
Ex. Grp #1–Individual InstructionGrp #2–Group Instructionn=30 in each group(could be 3000)RA, RS
Grp. #1 does 3 pts. better on posttest.Is that Significant?
What is the probability that observed differences between the Experimentalgroup and the Control group is due tochance?
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Probability (p)
p = (probability that difference is due to chance)[+ –] .0595% sure of significance
N.B.Level of significance is not levelof importance.
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Probability (p)
p = >.05 is the agreed upon standard >.07 is acceptable
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End part 2