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 absenttotalpositive84561645abnegative1613091325cdtotal10018701970

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 = 84b = 561c = 16d = 1309
Se = %
2.Easy
testdisease presentdisease absenttotalpositive134274408abnegative3612461282cdtotal17015201690

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 accuracy Acc as a percentage. Round to one decimal place.

a = 134b = 274c = 36d = 1246
Acc = %
3.Medium
peopleyears1200325901.531401.5new cases8

Practice exercise (made-up values, not clinical guidance). In a cohort, groups of people were followed for different lengths of time (see the table: number of people and years of follow-up for each). During follow-up, 8 new cases occurred. Find the incidence rate IR per 1000 person-years. Round to one decimal place.

200 × 3 years590 × 1.5 years140 × 1.5 years8 new cases
IR = per 1000 person-years
4.Medium
Se93%Sp60%LR+ = ?

Practice exercise (made-up values, not clinical guidance). A test has a sensitivity of 93% and a specificity of 60%. Find the positive likelihood ratio LR+. Round to two decimal places.

Se = 93%Sp = 60%
LR+ =
5.Hard
p (%)PPV (%)30%PPV = ?100

Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 94% and a specificity of 97%. It is used in a population where the prevalence is 30%. Find the positive predictive value PPV as a percentage. Round to one decimal place.

Se = 94%Sp = 97%p = 30%
PPV = %
6.Hard
CER21%EER?RRR 19%

Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 19% in relative terms (RRR = 19%). In a patient group the risk without treatment (CER) is 21% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.

RRR = 19%CER = 21%
NNT =

Answer key

  1. 1. Se = 84 %
  2. 2. Acc = 81.7 %
  3. 3. IR = 4.7 per 1000 person-years
  4. 4. LR+ = 2.33
  5. 5. PPV = 93.1 %
  6. 6. NNT = 26

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