standard deviation
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a numerical value that represents variability, approximately the average
distance that values will fall from the mean
- calculator for this
how do we determine the margin of error surrounding a sample statistic?
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(larger sample size) smaller SE -> narrower interval
(smaller sample size) larger SE -> wider interval
,95% interval
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statistic+- 2x SE
relative risk
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the ratio of the risks in two different categories of an explanatory variable
ex: relative risk of CHD for high anger compared to low anger
(high CHD/high total)/ (low CHD/low total)
quantitative variables
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-no minimum
-no maximum
-can be measured infinitely
-more precisely
confidence intervals (any confidence)
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, statistic +/- (z*)x SE
degrees of freedom for chi squared
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(#rows-1)x (#columns-1)
Apparently, sexual frustration increases the desire for alcohol, at least in fruit flies.
Scientists1 randomly put 24 fruit flies into one of two situations. The 12 fruit flies in the
''mating" group were allowed to mate freely with many available females eager to
mate. The 12 in the ''rejected" group were put with females that had already mated and
thus rejected any courtship advances. After four days of either freely mating or
constant rejection, the fruit flies spent three days with unlimited access to both
normal fruit fly food and the same food soaked in alcohol. The percent of time each
fly chose the alcoholic food was measured. The fruit flies that had freely mated chose
the two types of food about equally often, choosing the alcohol variety on average of
47% the time. The rejected males, however, showed a strong preference for the food
soaked in alcohol, selecting it on average 73% of the time. (The study was designed to
study a chemical in the brain called neuropeptide that might play a role in addiction.)
Give this one a try later!
Give this one a try later!
a numerical value that represents variability, approximately the average
distance that values will fall from the mean
- calculator for this
how do we determine the margin of error surrounding a sample statistic?
Give this one a try later!
(larger sample size) smaller SE -> narrower interval
(smaller sample size) larger SE -> wider interval
,95% interval
Give this one a try later!
statistic+- 2x SE
relative risk
Give this one a try later!
the ratio of the risks in two different categories of an explanatory variable
ex: relative risk of CHD for high anger compared to low anger
(high CHD/high total)/ (low CHD/low total)
quantitative variables
Give this one a try later!
-no minimum
-no maximum
-can be measured infinitely
-more precisely
confidence intervals (any confidence)
Give this one a try later!
, statistic +/- (z*)x SE
degrees of freedom for chi squared
Give this one a try later!
(#rows-1)x (#columns-1)
Apparently, sexual frustration increases the desire for alcohol, at least in fruit flies.
Scientists1 randomly put 24 fruit flies into one of two situations. The 12 fruit flies in the
''mating" group were allowed to mate freely with many available females eager to
mate. The 12 in the ''rejected" group were put with females that had already mated and
thus rejected any courtship advances. After four days of either freely mating or
constant rejection, the fruit flies spent three days with unlimited access to both
normal fruit fly food and the same food soaked in alcohol. The percent of time each
fly chose the alcoholic food was measured. The fruit flies that had freely mated chose
the two types of food about equally often, choosing the alcohol variety on average of
47% the time. The rejected males, however, showed a strong preference for the food
soaked in alcohol, selecting it on average 73% of the time. (The study was designed to
study a chemical in the brain called neuropeptide that might play a role in addiction.)
Give this one a try later!
