Term
why are statistics necessary |
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Definition
to understand the potential influence on experimental results and show that the treatment and only the treatment cause the effect or that the frequency of an event is attributable to a given factor. |
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Term
what does an experiment tell us about the effect of a treatment |
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Definition
it can only ESTIMATE the underlying effect of a treatment |
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Term
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Definition
a clear statment of what the investigators expect the study to find, testable |
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Term
what used to be the paradigm for statistical inference |
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Definition
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Term
what is the null hypothesis |
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Definition
there is no difference between outcomes due to the treatments being compared, in most research this is what you start out with, what you set to test |
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Term
what is the goal of hypothesis testing |
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Definition
calculate the probability of getting the observed results if the null hypothesis is true |
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Term
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Definition
in reality the null hypothesis is true but in experiment it suggests that an alternative hypothesis is true |
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Term
what does the P value show |
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Definition
tells how unlikley it is that the result occured simply by chance if the null hypothesis is true |
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Term
what P values are considered statistically significant |
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Definition
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Term
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Definition
in reality there is a difference between the two groups but when you do the research it says there isnt |
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Term
what happens to error when the sample size is too small |
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Definition
increased risk of type 2 error |
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Term
what happens to the error when the sample size is large |
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Definition
less risk of type two error |
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Term
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Definition
the probability of not comitting type 2 error |
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Term
what are the limitations to hypothesis testing |
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Definition
limits decision to yes or no, choice of p value significance seems arbitrary, cant inform as to wether or not the sample size is sufficient or if the results are definitive |
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Term
what is a confidence interval based on |
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Definition
observed result and the size of the sample |
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Term
what information does a confidence interval provide, how is it presented |
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Definition
gives range of possibilities in which the true probability would like within the 95% of the time |
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Term
what is the relation of confidence intervals to power |
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Definition
can determine if there is adequate power to make the results definitive, lets you know if there was enough people in the sample to make the study meaningful |
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Term
what does it mean when a conficence interval is not difinitive |
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Definition
the range is less than you stated. For example: you said it would be greater than a 5% difference but the CI shows a 2-10% difference |
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Term
what does it mean when a confidence interval is difinitive |
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Definition
the results fall within your projected value. for example: you say there 5% or greater difference and the CI shows 5-10% |
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Term
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Definition
if the lower boundry of a CI is greater than the smallest difference clinically significant, it is difinitive. if it is less it needs more trials |
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Term
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Definition
if less than the smallest difference that is clinically significant, it is definitive. if greater then more trials are needed |
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Term
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Definition
risk of the event after treatment as a percentage of the origional task |
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Term
what is absolute risk reduction |
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Definition
difference in the risk of the outcome between the two groups, aka risk difference |
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Term
what is relative risk reduction |
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Definition
estimates the percent of baseline risk that is removed as a result of the therapy |
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Term
what are the measures of association |
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Definition
absolute risk reduction, relative risk reduction, relative risk, odds ratio |
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Term
what measures of association stay the same no matter what group you look at (high risk or low risk patients) |
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Definition
relative risk reduction and relative risk |
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Term
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Definition
estimates the odds of an event occuring |
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Term
what types of studies are odds ratio used in |
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Definition
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Term
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Definition
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Term
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Definition
the ARR, absolute risk reduction |
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Term
what does a NNT of 6 mean |
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Definition
for every 6 good procedures you do you prevent a death from the old bad one |
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Term
what is a case control study |
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Definition
participants are selected based on an outcome or if they have experienced an event |
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Term
what does an odds ratio of 1 mean |
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Definition
there is no difference between the groups |
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Term
what does an odds ratio of > 1.2 mean |
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Definition
statistically signifianct difference between groups |
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Term
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Definition
you are more likley to disclose or remember information based on your disease |
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Term
what measure of association is the best in randomized and cohort studies |
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Definition
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Term
what do RR and RRR not count for |
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Definition
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Term
which measure of association is the best for case control studies |
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Definition
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Term
what does correlation and regression help us understand |
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Definition
relationship between variables, enables us to make perdictions about a given patient |
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Term
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Definition
the magnitude of the relationship between different variables, neither variable is the target |
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Term
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Definition
makes a perdiction or casual inference, one variable is the target |
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Term
what does a correation of -1 mean, what does it look like |
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Definition
strong negative correlation, line from upper left to bottom right |
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Term
what does a correlation of 1 mean, what does it look like |
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Definition
strong positive correlation, bottom left to top right |
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Term
what does a correlation of 0 mean, what does it look like |
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Definition
no correlation, scattered |
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Term
what can a correlation not distinguish |
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Definition
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Term
what is a multivariate regression |
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Definition
considers all of the independet variables in a mathematical model |
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Term
what conclusions should we take from the lecture (3) |
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Definition
make friends with statiticians, dont take statistical competence or honesty of authors for granted, shoot for proficiency in hypothesis testing, confiedence intervals, measures of association, and correlation and regression |
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