Statistics – Tests of significance

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Q) To Study the effect of an antiviral  drug, we note down the initial viral load and then after  a month repeat viral load. What is the   the most appropriate statistical test of significance to test the change in viral load

(a) Paired t-test
(b) Unpaired or independent t-test
(c) Analysis of variance
(d) Chi-square test

Ans a) Paired t test

paired t test is used When comparing the same person results after giving a drug or doing a surgery or any intervention

A paired t-test is used when we are interested in the difference between two variables for the same subject. Often the two variables are separated by time

Unpaired t test

The unpaired two-samples t-test is used to compare the mean of two independent groups.

For example, suppose that we have measured the weight of 100 individuals: 50 women (group A) and 50 men (group B). We want to know if the mean weight of women  is significantly different from that of men In this case, we have two unrelated (i.e., independent or unpaired) groups of samples. Therefore, it’s possible to use an independent t-test to evaluate whether the means are different.

Chi-square test

The basic idea behind the test is to compare the observed values in your data to the expected values that you would see if the null hypothesis is true.

To determine whether the association between two qualitative variables is statistically significant

Analysis of Variance ANOVA example

A group of psychiatric patients are trying three different therapies: counseling, medication and biofeedback. You want to see if one therapy is better than the others.


Southampton wound grading system.

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Q) As per Southampton wound grading system, clear or haemoserous discharge Along wound (>2 cm) is 

a) IIb

b) IIB

c) IIIa



Catheter Related sepsis

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Q ) Not True about catheter related sepsis in TPN? (More Questons on  INFECTIONS) 

a) Catheter-related sepsis occurs in 3–14% of patients.

b) It  occurs both  at the time of line insertion or afterwards by migration of skin bacteria along the external catheter surface.

c)It can occur from bacteraemia from a remote source may also cause catheter infection.

d) Catheter should be removed in all cases


Post op pulmonary complications

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Q) What does not decrease post op pulmonary complications? ( Questions on Gen Surgery Peri op care)  

a) Smoking cessation

b) Epidural Anesthesia

c) Nasogastric tube

d) Preop and post op Spirometry

Ans c) Routine Naso gastric tube placement

Postoperative pulmonary complications occur in approximately 6% of patients after major abdominal operations and

It includes pneumonia/infection, respiratory failure requiring prolonged ventilation, exacerbation of chronic obstructive pulmonary disease (COPD), and lobar/parenchymal collapse with or without associated effusion.

More recently, standard patient care protocols (e.g., iCough) have been developed to decrease the risk of pulmonary complications, which include incentive spirometry, coughing and deep breathing, oral care
(brushing teeth and using mouthwash), elevating the head of bed,
and getting out of bed three times a day.

Multimodal pain control
and judicious use of regional analgesia (e.g., thoracic epidurals) may
also help to prevent pulmonary complications in surgical patients.
Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice

Ref Sabiston 21 page 247

Short Term Nutrition

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Q  Best indicator to assess short term nutritional status is 

a) Albumin

b) Pre albumin

c) Transferrin

d) Any can be used