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.

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
testdisease presentdisease absenttotalpositive232258490abnegative38502540cdtotal2707601030

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 = 232b = 258c = 38d = 502
Se = %
2.Easy
testdisease presentdisease absenttotalpositive60114174abnegative3013161346cdtotal9014301520

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 = 60b = 114c = 30d = 1316
Sp = %
3.Medium
eventno eventtotaltreatment28872360abcontrol200300500cd

Practice exercise (made-up values, not clinical guidance). In a randomised trial, 360 patients received a new treatment and 500 received the control treatment. The table shows how many in each group had a side effect. Find the number needed to harm NNH: how many patients must be treated for one extra patient to have the side effect? Round up to a whole number of patients.

treatment: 288/360control: 200/500
NNH =
4.Medium
testdisease presentdisease absenttotalpositive337146483abnegative33394427cdtotal370540910

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 negative likelihood ratio LR−. Round to two decimal places.

a = 337b = 146c = 33d = 394
LR− =
5.Hard
pre-test25%post-test?p′LR+

Practice exercise (made-up values, not clinical guidance). A patient has a pre-test probability of 25% for a disease. A test with sensitivity 84% and specificity 66% comes back positive. Find the post-test probability p′ of the disease as a percentage. Round to one decimal place.

pre-test 25%Se = 84%Sp = 66%positive
p′ = %
6.Hard
pre-test20%post-test?p′LR−

Practice exercise (made-up values, not clinical guidance). A patient has a pre-test probability of 20% for a disease. A test with sensitivity 74% and specificity 89% comes back negative. Find the post-test probability p′ of the disease as a percentage. Round to one decimal place.

pre-test 20%Se = 74%Sp = 89%negative
p′ = %

Answer key

  1. 1. Se = 85.9 %
  2. 2. Sp = 92 %
  3. 3. NNH = 3
  4. 4. LR− = 0.12
  5. 5. p′ = 45.2 %
  6. 6. p′ = 6.8 %

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