PowerPoint Presentation Nature of Research Pt.2

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Nature of Research Pt 2
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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 ofExplication 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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HYPOTHESIS
Must be specific expression of expected
answer about relationships among variables.
Interaction of operational definitions,
concrete, observable.
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HYPOTHESIS
From testing of the hypothesis one draws
inferences which may allow generalization
based on the theory.
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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
Group watches 3 hrs. of violent tv.
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VALIDITY External
Ex. Study of violent tv watching. Experimental
Group watches 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 be measured? 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 History If 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 Testing All
participants must be sensitized to the same
extent.
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Threats to Internal Validity
Mortality If dropouts are not equally
distributed (randomly) there may be systematic
bias.
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Threats to Internal Validity
Maturation Participants 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 from each
ethnic, racial, age, class, etc., group. Allows
validity with only 1100 polled of 260 million.
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Precision
Difference between groups _______________________
Difference between individuals within group

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Precision
D B _____ D W
Probability (p)

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Standard Deviation
Size of variability of distribution of individual
differences. Mean (x) yields some
information, not necessarily meaningful. Range
tells more of the story.
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Standard Deviation
A B
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Standard Deviation
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Standard Deviation
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6 7 8 9 10 11 12
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Standard Deviation
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6 7 8 9 10 11 12
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Standard Deviation
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6 7 8 9 10 11 12
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Standard Deviation
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6 7 8 9 10 11 12
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Standard Deviation
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6 7 8 9 10 11 12
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Statistical Significance
Significance of difference or,
meaningfulness.
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Statistical Significance
Ex. Grp 1Individual Instruction Grp
2Group Instruction n30 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 1Individual Instruction Grp
2Group Instruction n30 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 Experimental group and
the Control group is due to chance?
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Probability (p)
p (probability that difference is due to
chance) .05 95 sure of significance N.B. L
evel of significance is not level of importance.
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Probability (p)
p gt.05 is the agreed upon standard gt.07
is acceptable
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End part 2