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Updated: Monday, April 12, 1999 10:49:58 AM
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Section 1:
Scientific
Method & Experiments
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Controlling for
Expectation |
Single
Blind - The
participant does not know
if he or she is receiving
the active treatment or
the placebo
(example:
sugar pills)
Double Blind -
Neither the participant
nor the person
adminstering the
experiment knows who is
getting what.
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Random Selection
– Every subject has
an equal chance to be in
the experiment.
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| Determining
a correlation: |
Representation of a relationship
Correlation
coefficient.
R = +.37
Smallest value = -1
Largest = +1 |
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example a correlation
that does NOT imply
causation: |
There is a correlation
between eating sugar
frosted flakes for
breakfast and having less
cancer. That is people
who ate sugar frosted
flakes have a reduced
chance of acquiring
cancer. But sugar
frosted flakes does
not cause
less cancer.
Explanation of
correlation without
causation in this
example:
The relationship between
eating Sugar fosted
flakes is due to the age
of the participants.
The fact that
sugar frosted flakes are
so new means that most
people who started eating
the cereal are still young
and healthy (and have not
come down with cancer yet),
whereas, partipants who
did not eat sugar forsted
flakes (because they were
not available yet) are
now old and dying of
cancer.
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time
order: the
manipulation comes before
it's effect
manipulation:
changing the stimulus
to which subjects respond
in one group and not
changing it in another
group. To avoid
these problems perform a
"True"
experiment must use manipulation.
This involves
changing the stimulus to
which subjects respond,
assuring time
order and
also random assignment
assures that the two
groups are equal to each
other before the
manipulation begins.
Random assignment means
that each subject had an
equal chance of being in
each condition of the
experiment.
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| Example: |
Test people for
Alcohol related Violence:
Some
with No Alcohol (0 ounces
of alcohol (control))
Some
with Alcohol (1 ounce of
alcohol)
Some
with More Alcohol (8
ounces of alcohol
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| How are
we going to change
violence (dependent
variable) into a
number? |
Each time the person
raises their voice and it
will be counted as one
violent action.
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| There
are a number of possible operational
definitions of
violence
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| Abstract
of a Correlational study
presented in lecture: |
Key
Term:
MR:
Magnetic Resonance Image
Study
About:
Cerebral
N-Acetylaspartate is low
in patients with multiple
Sclerosis and abnormal
Visual Evoked Potentials
(VEP’s)
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| Purpose: |
Our
purpose was to compare
cerebral proton MR
metabolite changes in
patients with multiple
sclerosis MS and abnormal
visual evoked potentials
(VEP’s) with those
in ms patients with
normal VEP’s |
| Methods: |
seventeen
subjects with clinically
definite MS were studied
with VP’s and MR
spectroscopic imaging.
Proton MR metabolites
were measured using a
fast spectroscopic
imaging technique called
proton echo-planar
spectroscopic imaging
PEPSI. Kurtzke’s
Expanded Disability
Status Scale (EDSS) score
was also ascertained for
each subject to obtain a
evaluated for levels of
N-Acetylaspartate,
choline, creatine, and
the presence or absence
of MR-detectable lesions |
| Result: |
PEPEI NAA
values (Water-normalized,
CSF-corrected were
significant lower in ms
subjects with abnormal
VP’s than in
subjects with normal
VEP’s. MR-detectable
lesion factors and EDSS
Scores were also
significantly different
between the two VEP
groups, but NAA
comparison and a P value
100 times less than
either of these measures. |
| Conclusion: |
In
patients with MS, NAA
measurements in the optic
pathways of the brain,
were sensitive to VEP
abnormalities. NAA was
more sensitive to VEP
changes than were choline
creatine, MR-detectable
lesions and EDSS score. |
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