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#1
01-28-2011
 USMLE Forums Scout Steps History: Not yet Posts: 12 Threads: 1 Thanked 19 Times in 6 Posts Reputation: 29
parameters of sensitivity and specificity

I couldn't understand this question!
the parameters of sensitivity and specificity are used for assessing?
1. criterion validity
2. construct validity
3. discriminant validity
4. content validity

and while your at it... here is another question.... just a random one.
calculation of a sample size for a prevalence study all of the following are necessary except..
1. prevalence of the disease in population
2. power of the study
3. significance level
4. desired precision

#2
01-28-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,175 Threads: 38 Thanked 852 Times in 478 Posts Reputation: 862

a) 4

b) 4

Not too sure about B) though
#3
01-28-2011
 USMLE Forums Scout Steps History: Step 1 Only Posts: 61 Threads: 3 Thanked 76 Times in 29 Posts Reputation: 86
Not high yield

Where did you get these questions from for God's sake!
The various types of validity have never been tested in the USMLE exam ever.
Even the most expert statisticians are confused about these.
Moreover, I think the question is wrong because specificity and sensitivity are other measures of the validity of the test and they are not categorized into any of the options you listed.
 The above post was thanked by: aktorque (01-30-2011), gargabhi2 (01-28-2011)

#4
01-28-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,175 Threads: 38 Thanked 852 Times in 478 Posts Reputation: 862

Quote:
 Originally Posted by Dulbee Where did you get these questions from for God's sake! The various types of validity have never been tested in the USMLE exam ever. Even the most expert statisticians are confused about these. Moreover, I think the question is wrong because specificity and sensitivity are other measures of the validity of the test and they are not categorized into any of the options you listed.

I think with the first question, its basically asking you whether you know what information is gained from Specificity and Sensitivity, which I think is not tested, but everyone should know anyways.

The question two is just weird, I guessed!

On another note:

Is biostats and Epidemio THAT important on Step 1? I sucked at the kaplan practice questions (in the lecture notes)
#5
01-28-2011
 USMLE Forums Scout Steps History: Step 1 Only Posts: 61 Threads: 3 Thanked 76 Times in 29 Posts Reputation: 86

Quote:
 Originally Posted by patelMD I think with the first question, its basically asking you wether you know what information is gained from Specificity and Sensitivity, which I think is not tested, but everyone should know anyways. The question two is just weird, I guessed! On another note: Is biostats and Epidemio THAT important on Step 1? I sucked at the kaplan practice questions (in the lecture notes)
Yes it's high yield, but absolutely not such kind of questions.
#6
01-29-2011
 USMLE Forums Veteran Steps History: 1+CK+CS Posts: 244 Threads: 16 Thanked 198 Times in 86 Posts Reputation: 208

Quote:
 Originally Posted by manphnx I couldn't understand this question! the parameters of sensitivity and specificity are used for assessing? 1. criterion validity 2. construct validity 3. discriminant validity 4. content validity and while your at it... here is another question.... just a random one. calculation of a sample size for a prevalence study all of the following are necessary except.. 1. prevalence of the disease in population 2. power of the study 3. significance level 4. desired precision

first one is easy
3. Discrimination, also read up on ROC curves.. receiver operator characteristics.

second one is a weird. significance level makes no sense for a prevalence study !! LOL.. a significance level means that a "difference" is not by chance..

anyway stop doing these confusing questions. I did these during my MPH at johns hopkins... these are not USMLE level.
#7
01-31-2011
 USMLE Forums Scout Steps History: Not yet Posts: 12 Threads: 1 Thanked 19 Times in 6 Posts Reputation: 29

Quote:
 Originally Posted by drarnab first one is easy 3. Discrimination, also read up on ROC curves.. receiver operator characteristics. second one is a weird. significance level makes no sense for a prevalence study !! LOL.. a significance level means that a "difference" is not by chance.. anyway stop doing these confusing questions. I did these during my MPH at johns hopkins... these are not USMLE level.
well! i guess i owe u guys an apology... i just posted these questions just for discussion purposes. i thought there might be a hidden concept that i m missing....

any ways the answer to the first question is 1. (as given in the book, just matter of factly)
and answer to the second question is 'power of study'
explanation:
factors determining the sample size include.
1. design of study
2. plan of statistical analysis
3. accuracy of measurement to be made
4. degree of precision required
5. degree of significance
6. ratio of cases to controls in a case control study or prevalence of a disease in a cohort study

power of the study is the ability of a statistical test to detect a null hypothesis that is false and the probablility that a false null hypothesis is rejected

 Tags Biostatistics-Epidemiology, Step-1-Questions

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