Exam questions in Statistics and evidence-based medicine, spring sem. Medis/Medicin, Modul 2.4.

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1 Exam questions in Statistics and evidence-based medicine, spring sem. Medis/Medicin, Modul 2.4. MUPTIPLE HOIE QUESTION 1. Identify the false statement: D E Power = [1 - (probability of a Type II Error)] Errors are less common when big samples are used Type I error is mistakenly rejecting the null hypothesis when it is actually false Studies with small sample sizes tend to have low power Type II error is mistakenly accepting the null hypothesis when it is false Max point: 4 chieved point: MUPTIPLE HOIE QUESTION 2. Researchers conduct a randomized control trial comparing subjects on drug vs. drug in stroke prevention. They determine that 200 subjects, 100 subjects in each group, are required to have a power of 90% to detect a true difference of 5% or more. One percent of the subjects on drug developed a stroke while 4% of the subjects on drug developed a stroke. The significance level (lpha) was set at 0.05 and the resulting p-value was Select the true statement: The researchers should reject the null hypothesis Given the null hypothesis is correct, the probability of obtaining a difference of 5% or more is 7% The study s power to detect a true difference of 5% or larger is 80% D The significance level of the test is 3% E Given the null hypothesis is correct, the probability of obtaining a difference of 3% or more is 7% E Max point: 12 chieved point: 1

2 MUPTIPLE HOIE QUESTION 3. Select the best statement: D randomized control trial allows random allocation to intervention groups randomized control trial allows to demonstrate causality randomized control trial allows rigorous evaluation of a single variable randomized control trial allows control over unmeasured confounding E all above E Max point: 3 chieved point: ESSY-TYPE QUESTION 4. In a country, where the legal limit for drunken driving is 0.05 %, a man was brought in on suspicion of drunken driving. lcohol concentration in his blood was measured 7 times with following results: 0.055, 0.047, 0.057, 0.048, 0.053, and (bbreviations used: SD=standard deviation; I=confidence interval) Questions: a) Using SPSS (or another software), represent the data on alcohol concentration in his blood in a box-plot. ased on the boxplot obtained, make conclusions about the data. (Hint: describe a measure of central location, range, inter-quartile range, skewness, and potential outliers). b) alculate a sample mean alcohol concentration, a sample SD, and a 95% I for the mean alcohol concentration. Interpret the sample SD and I. c) Using your software, represent the I graphically. What commands (for example, in SPSS) did you use to build this interval? d) ased on the I obtained, would you convict the man? Why? Max point: 22 chieved point: 2

3 ESSY-TYPE QUESTION 5. teacher conducted an experiment to test whether new directed reading activities in the classroom will help elementary school pupils improve their reading ability. She arranged for a class of 11 students ( treatment group) to follow these activities for an 8-week period. control class of 10 students ( control group) followed the same curriculum without the activities. (The two groups of students were selected independently with no attempt to match). The experiment was ended by a test, where the students were asked to read a text. The reading time (in minutes) was measured and registered in the table below. Reading Reading Time Time [min.] Group [min.] Group 5 treatment 7 control 6 treatment 7 control 6 treatment 8 control 7 treatment 8 control 7 treatment 8 control 7 treatment 9 control 8 treatment 9 control 8 treatment 9 control 9 treatment 10 control 9 treatment 10 control 10 treatment Questions: a) What test would you perform to compare reading time in two groups of students? b) What are the assumptions for this test? Show, whether the data satisfy the assumptions for the test. c) What null hypothesis do you choose for your test? d) Perform the test and outline the main results. e) Explain (interpret) the results. f) What is your conclusion about the effect of new directed reading activities on pupils reading ability? Why? Max point: 22 chieved point: 3

4 ESSY-TYPE QUESTION 6. The table below contains measurement of body temperature in 15 patients using an oral thermometer and a rectal thermometer. Patient ID Oral temperature Rectal temperature 1 37,1 38,1 2 37,8 38,1 3 38,2 38,9 4 38,2 38,4 5 40,0 40,1 6 38,5 38,9 7 36,5 37,1 8 37,6 37,8 9 37,1 37, ,2 36, ,9 37, ,5 38, ,5 37, ,5 37, ,5 38,9 Questions: a) What test would you perform to compare temperature measured by two different thermometers? b) What are the assumptions for this test? Show, whether the data satisfy the assumptions for the test. c) What null hypothesis do you choose for your test? d) Perform the test and outline the main results. e) Explain (interpret) the results. f) What is your conclusion about the difference in temperature measurements using the oral and rectal thermometers? Why? Max point: 22 chieved point: 4

5 EXTENDED MTHING 7. Evidens Fejlkilder:. ias. Statistisk usikkerhed Opgave: Vælg fra listen af fejlkilder den, der passer bedst til hvert af de nedenstående udsagn. Giver en ringe validitet (pålidelighed nøjagtighed) Kan reduceres ved omhyggelig planlægning af forsøg Giver en ringe præsicion (sikkerhed) Kan reduceres ved statistiske beregninger Risikoen reduceres, hvis alle i stikprøverammen har den samme sandsynlighed for at blive udtrukket til stikprøven Risikoen reduceres, hvis stikprøverammen = målpopulationen Max point: 3 Reduceres hvis stikprøvestørrelsen øges 5

6 EXTENDED MTHING 8. Evidens egreber:. De epidemiologiske metoderegler. Evidensbaseret medicin. Evidensbaseret praksis D. Systematiske reviews E. Evidensbaseret viden Opgave: Vælg fra listen af begreber det, der passer bedst til hvert af de nedenstående udsagn. Viden af høj kvalitet i forhold til de epidemiologiske metoderegler E Danner grundlag for bedømmelsen af kvaliteten af egne- og andres studier efinder sig på det højeste evidensniveau i Oxford entre for Evidence- ased Medicine s skema til graduering af evidensen i epidemiologiske undersøgelser nvendelse af evidensbaseret viden (hvor en sådan findes) som basis for Sundhedsvæsenets tilbud/ydelser nvendelse af en kombination af viden af høj kvalitet, lægens ekspertise og patientens præferencer Knytter epidemiologi, statistik og evidens sammen D Indeholder al eksisterende evidens indenfor et område herunder statistiske beregninger nvendelse af referenceprogrammer og evidensbaserede kliniske vejledninger Max point: 3 D 6

7 MULTIPLE HOIE QUESTION 9. Hvilken type evidens rangerer højest i valg af klinisk behandling? Ekspert Viden ase-control studier Systematiske reviews D Dobbelt blindede kohorte studier E Randomiserede kontrollere forsøg (RT) Max point 2 EXTENDED MTHING 10. Evidens egreber:. Referenceprogrammer. Kliniske vejledninger. Procedurer Opgave: Vælg fra listen af begreber det, der passer bedst til hvert af de nedenstående udsagn. Er tværfaglige Er evidensbaserede ngiver arbejdsprocesser i forbindelse med undersøgelse, behandling og pleje Vedrører faglige ydelser og anviser beslutning om klinisk adfærd i givne kliniske situationer Indeholder organisatoriske og økonomiske overvejelser Indeholder patientsynspunkter Er monofaglige Max point: 3 7

8 MULTIPLE HOIE QUESTION 11. Nedenstående udsagn angiver en række grunde til, at evidensbaseret praksis ikke udøves rutinemæssigt overalt i sundhedsvæsenet, hvilken er IKKE korrekt? Gamle vaner Der findes ikke evidensbaseret viden indenfor alle medicinske fagområder endnu Eksplosiv udvikling i antallet af behandlingstilbud D Manglende motivation E Manglende tid Max point 2 MULTIPLE HOIE QUESTION 12. Hvilken medicinsk database er kendt for at stille specielt høje krav til, at de epidemiologiske metoderegler er overholdt? Signahl ochrane Embase D e-medicine E Medicin.dk Max point 2 8