Evidence-based practice statistics worksheet with answers

Free printable Evidence-based practice statistics worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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Name: ____________________   Date: ____________

1.Easy
testdisease presentdisease absenttotalpositive388390778abnegative12910922cdtotal40013001700

Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the specificity Sp as a percentage. Round to one decimal place.

a = 388b = 390c = 12d = 910
Sp = %
2.Easy
testdisease presentdisease absenttotalpositive134237371abnegative86893979cdtotal22011301350

Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the sensitivity Se as a percentage. Round to one decimal place.

a = 134b = 237c = 86d = 893
Se = %
3.Medium
eventno eventtotaltreatment114646760abcontrol270630900cd

Practice exercise (made-up values, not clinical guidance). In a randomised trial, 760 patients received a new treatment and 900 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the relative risk reduction RRR as a percentage. Round to one decimal place.

treatment: 114/760control: 270/900
RRR = %
4.Medium
casescontrolsexposed11637abnot exposed3443cd

Practice exercise (made-up values, not clinical guidance). A case-control study compares 150 patients with a disease (cases) and 80 people without it (controls). The table shows how many in each group were exposed to a risk factor. Find the odds ratio OR for the exposure. Round to two decimal places.

a = 116b = 37c = 34d = 43
OR =
5.Hard
testdisease presentdisease absenttotalpositive?negativetotal10 000

Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 89% and specificity 78%. The prevalence of the disease is 22%. How many false-positive results FP are expected?

N = 10 000p = 22%Se = 89%Sp = 78%
FP =
6.Hard
control23%treatment?

Practice exercise (made-up values, not clinical guidance). Without a drug, 23% of patients have a certain side effect during a year. The drug raises this risk with a relative risk of RR = 1.25. Find the number needed to harm NNH: how many patients must take the drug for a year for one extra patient to have the side effect? Round up to a whole number of patients.

control 23%RR = 1.25
NNH =

Answer key

  1. 1. Sp = 70 %
  2. 2. Se = 60.9 %
  3. 3. RRR = 50 %
  4. 4. OR = 3.97
  5. 5. FP = 1716
  6. 6. NNH = 18

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