shirini2
Forum Senior
Topics: 27
Posts: 86
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A study reports that 65 of 100 patients with multiple sclerosis have cats as household pets. The authors conclude that exposure to cats causes multiple sclerosis. Which one of the following statements can be made about the authors' conclusions?
1) correct, because it is specific for the study population
2) correct, because the comparison is based on exposure rates
3) incorrect, because of the failure to carry out an appropriate statistical analysis of the data
4) incorrect, because the sample size is too small to permit generalization to the entire population of multiple sclerosis patients
5) incorrect, because of the lack of an appropriate control or comparison group
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| sprint123
Forum Guru
Topics: 129
Posts: 870
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5 ----- Controls are like GODS 
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| shirini2
Forum Senior
Topics: 27
Posts: 86
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how about sample size?
confused between sample size and control 
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| sprint123
Forum Guru
Topics: 129
Posts: 870
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sample size refers to both cases and controls. For example, if sample size , n = 1000 , it means that the total number of cases and controls is 1000.
Controls are a part of the sample size, n.
A clinical trial has two validities. Internal and external validity. Internal validity determines the validity of the sudy design and external validity deals with generalizability.
In this study, the design is not internally valid due to lack of controls and hence there is no question on external validity.
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| shirini2
Forum Senior
Topics: 27
Posts: 86
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Thank you.
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| anastamosis
Forum Senior
Topics: 34
Posts: 167
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Wow SPRINT 123, what did u read for biostats?
SHRINI2 , is the Question from UW Q bank?
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THE HIGHER YOU AIM, THE HIGHER YOU REACH !! My contacts are as follows ==> yahoo id --> anastamosis_e2e;gmail id --> anastamosis;Skype id --> anastamosis
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| shirini2
Forum Senior
Topics: 27
Posts: 86
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No, it's from canadian self administered examination.
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