Statistics Questions asked in Surgery Exams

Questions on Statistics

Q1 All are true except:
a. Senisitivity tp/tp+fn

b. Specificity tn/tn+fn

c. Ppv tp/tp+fp

d. Npv tn/tn+fn

Important Statistics for Surgeons

A) Comparing  outcomes

Tests of Significance to compare two 

  1. Student t test - Also called two sample t test , compares mean of two Independent  groups. For this you require two mean values, two sample variance and total no. of objects in the sample


B) Sensitivity, Specificity , PPV and NPV

You will have to remember the formulas like in the olden times of PHysics and Maths

Make a 2X 2 table  TP is True positive and so on, 

                           A (TP)                                   B (FP)


                          C (FN)                                   D ( TN) 


Case Control vs Cohort Studies

In case control studies, patients with the disease of interest (diabetes) are selected from a population and compared with representative ( same age and sex) , non diseased individuals from the same population.

There are several advantages of case-control studies.