Q: In a Normal Distribution Curve, The area to the left of 1SD is:

a. 0.16
b. 0.34
c. 0.45
d. 0.84

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Ans: d. 0.84

total area = 1;

area to left of median = 0.5;

area between median and +1SD = 0.34;

so total area to left of +1SD = 0.5 + 0.34 = 0.84

Q. In random sampling chance of being picked up is:

a. same n known
b. not same n not known
c. not same but known
d. same n not known

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Ans : c

There are two types of random sampling: with replacement and without replacement.

With Replacement:

Sampling is called with replacement when a unit selected at random from the population is returned to the population and then a second element is selected at random. Thus a unit may be selected more than once. There is no change at all in the size of the population at any stage. This is only a “theoretical concept” and in practical situations the sample is not selected by using this method.

Without Replacement:

Sampling is called without replacement when a unit is selected at random from the population and it is not returned to the main lot. First unit is selected out of a population of size N and the second unit is selected out of the remaining population of (N−1) units and so on.

So the chance of being picked up by the first unit of sample will be 1/ N.

Similarly,

the chance of being picked up by the second unit of sample will be 1/ (N-1)

the chance of being picked up by the third unit of sample will be 1/ (N-2) and so on.

Thus the chance of being picked up is not the same for each unit but is known (Option C)

None of the following methods can show relationship between two variables except ?

a)      Histogram

b)      Line diagram

c)       Bar chart

d)      Scatter plot

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Ans: d

 Scatter plot can be used to reveal relationships between 2 quantitative variables. The hypothesized exposure variable (cause or independent variable) is plotted on X axis and the effect variable (dependent variable) is plotted on Y axis. A dot or point is plotted for each pair of observations. If the dots of all the observations fall along a line (or a curve), we could conclude that there is a correlation between the 2 variables.

Sentinel surveillance of hiv is done for all except?

a. Disease trend
b. High risk group
c. Monitor effectiveness of control program
d. Population at risk

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Ans: d

 

 

 

v HIV Sentinel Surveillance (HSS) in India:

1. Started in 1998. 13 rounds completed so far.
2. The overall HIV prevalence among ANC clinic attendees is considered a proxy for prevalence among the general population,
3. HIV estimates of prevalence, incidence and mortality developed based on findings from HIV Sentinel Surveillance enable the programme in assessing the impacts at a macro level. Provides essential information to understand the trends and dynamics of HIV epidemic among different risk groups in the country.
4. The 13 round of HSS was implemented during 2012-13 where HIV prevalence among ANC clinic attendees was 0.35%. The highest prevalence was recorded in Nagaland (0.88%)

 

Highlights of Methodology of HSS at each ANC Clinics site

• Sample Size: 400 per HSS site
• Duration: 3 months at each HSS site
• Frequency: Every 2 yearly
• Sampling Method: Consecutive
• Inclusion Criteria: Pregnant Women, aged 15-49 years, attending the antenatal clinic for the first time during HSS period
• Testing Strategy: Unlinked Anonymous
• Testing Protocol: Two Test Protocol

 

v  Integrated Biological and Behavioral Surveillance (IBBS):

The high risk groups and bridge population that National IBBS covers across the country are

1. Female Sex Workers (FSW),
2. Men who have Sex with Men (MSM),
3. Trans-genders (TG),
4. Injecting Drug Users (IDU),
5. Migrants (MIG) and
6. Currently Married Women (CMW) (not ANC mothers)

 

v  Current HIV Prevalence Statistics:

• ANC                                            : 0.35 %
• Migrants                          : 0.99%
• Truckers                          : 2.59%
• Female Sex Workers    : 2.67%
• Men Having Sex with Men      : 4.43%
• Injectable Drug Users  : 7.14%
• Transgenders                : 8.82%

The extent to which a specific health care treatment, service, procedure, program, or other intervention produces a beneficial result under ideal controlled conditions is its:

a. Effectiveness

b. Efficacy

c. Efficiency

d. Effect modification

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Ans: b. Efficacy

v  Efficacy (Potency) is the extent to which a specific intervention, procedure, or service produces the desired effect, under ideal conditions (controlled environment, lab circumstances). An efficacy study asks the question, "Does the vaccine work?"

v  Effectiveness is the extent to which a specific intervention, procedure, or service produces the desired effect, under ordinary conditions (real life, not controlled). an effectiveness study asks the question "Does vaccination help people?"

v  Efficiency is the ratio of the output to the inputs of any system. When outputs > inputs, then system is highly efficient.

Eg:

Vaccine efficacy shows how effective the vaccine could be given ideal circumstances and 100% vaccine uptake; 

Vaccine effectiveness measures how well a vaccine performs when it is used in routine circumstances in the community

Note:

Clinical Trial Phase I :  Safety Trial

Clinical Trial Phase II: Immunogenicity Trial

Clinical Trial Phase III: Efficacy Trial

Clinical Trial Phase IV: Effectiveness Trial

Randomization is the best approach in designing a clinical trial in order to

a. Achieve predictability

b. Achieve unpredictability

c. Achieve blinding

d. Limit confounding

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Ans: b. Achieve unpredictability

Recall is an example of:

a. Selection bias

b. Information bias

c. Confounding

d. Systematic

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Ans: b. Information Bias.