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
- 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.