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