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 absenttotalpositive266553819abnegative9410271121cdtotal36015801940

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 = 266b = 553c = 94d = 1027
Se = %
2.Easy
testdisease presentdisease absenttotalpositive165166331abnegative105524629cdtotal270690960

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 = 165b = 166c = 105d = 524
Sp = %
3.Medium
eventno eventtotaltreatment152798950abcontrol316474790cd

Practice exercise (made-up values, not clinical guidance). In a randomised trial, 950 patients received a new treatment and 790 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the number needed to treat NNT to prevent one event. Round up to a whole number of patients.

treatment: 152/950control: 316/790
NNT =
4.Medium
eventno eventtotaltreatment37573610abcontrol87783870cd

Practice exercise (made-up values, not clinical guidance). In a randomised trial, 610 patients received a new treatment and 870 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the number needed to treat NNT to prevent one event. Round up to a whole number of patients.

treatment: 37/610control: 87/870
NNT =
5.Hard
p (%)NPV (%)2%NPV = ?100

Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 93% and a specificity of 85%. It is used in a population where the prevalence is 2%. Find the negative predictive value NPV as a percentage. Round to one decimal place.

Se = 93%Sp = 85%p = 2%
NPV = %
6.Hard
pre-test40%post-test?p′LR+

Practice exercise (made-up values, not clinical guidance). A patient has a pre-test probability of 40% for a disease. A test with sensitivity 81% and specificity 63% comes back positive. Find the post-test probability p′ of the disease as a percentage. Round to one decimal place.

pre-test 40%Se = 81%Sp = 63%positive
p′ = %

Answer key

  1. 1. Se = 73.9 %
  2. 2. Sp = 75.9 %
  3. 3. NNT = 5
  4. 4. NNT = 26
  5. 5. NPV = 99.8 %
  6. 6. p′ = 59.3 %

Full step-by-step solutions: practise this topic on examproblems.com.