Q-121. Which is the best distribution to study the daily admission of head injury patients in a trauma care centre?
a) Normal distribution
b) Binomial distribution
c) Uniform distribution
d) Poisson distribution
Answer: Poisson distribution
Explanation:
The Poisson distribution is used to model the number of events occurring within a given time interval.
Q-122. Mean bone density amongst two groups of 50 people each is compared with each other. The test of significance used would be
a) Paired-t-test
b) Student-t-test
c) Analysis of variance
d) Chi-square test
Answer: Student-t-test
Explanation:
The student’s t-test is a statistical method that is used to see if two sets of data differ significantly.
Q-123. After applying a statistical test, an investigator gets the p value as 0.01. It means that
a) The probability of finding a significant difference is 1%
b) The probability of declaring a significant difference when there is truly no difference is 1%
c) The difference is not significant 1 % times and significant 90 % times
d) The power of the test used is 99 %
Answer: The difference is not significant 1 % times and significant 90 % times
Explanation:
The p-value is defined as the probability of obtaining a result equal to or “more extreme” than what was actually observed, when the null hypothesis is true.
Before performing the experiment, one first chooses a model (the null hypothesis) and a threshold value for p, called the significance level of the test, traditionally 5% or 1% and denoted as α (Alpha).
If the p-value is less than or equal to the chosen significance level (Alpha), the test suggests that the observed data is inconsistent with the null hypothesis, so the null hypothesis must be rejected and not rejected when p > α (Alpha).
Important point:
The p value of 0.01 i.e. 1 % means that there is 1 % chance of chance of null hypothesis being true.
Q-124. If mean is less than the median then the data is said to be
a) Positively skewed
b) Negatively skewed
c) Equitable distribution
d) Normal distribution
Answer: Negatively skewed
Explanation:
Relationship between the measures of central tendency:
Symmetrical curve: Mean = median = mode
Positive or right skewed curve: Mean > median > Mode
Negative or left skewed curve: Mean < median < Mode
Q-125. Study done on a group of patients showed coefficient of variance for BP and serum creatinine to be 20% & 15% respectively. Inference is that
a) Variation in BP is more than in serum creatinine
b) Variation in serum creatinine is more than in BP
c) Standard deviation of BP is more than of creatinine
d) Standard deviation of creatinine is more than of BP
Answer: Variation in BP is more than in serum creatinine
Explanation:
Coefficient of variance:
The coefficient of variation also known as relative standard deviation (RSD), is a standardized measure of dispersion of a probability distribution or frequency distribution.
It is often expressed as a percentage, and is defined as the ratio of the standard deviation to the mean.
The higher the coefficient of variance, the greater the dispersion in the variable
The advantage of the CV is that it is unit-less.
Q-126. In a study in UK, an association was found between sale of anti-arrhythmic drug and increases in deaths due to asthma. This is an example of
a) Ecological study
b) Cohort study
c) Case reference study
d) Experimental study
Answer: Ecological study
Explanation:
Ecological Study:
A study in which at least one variable is measured at the group (not individual) level.
Examples of group-level measures include the rate of cancer incidence, the mean level of hypertension or even the preventive service included in a health insurance plan.
The occurrence of disease is compared between groups that have different levels of exposure, thus offering a comparison group for this study design.
Q-127. Occupational cancer involve following organs
a) Lung
b) Breast
c) Bladder
d) Liver
Answer: Breast
Explanation:
Organs involved in occupation cancer:
Skin (Most common occupational cancer)
Bladder
Lung and mesothelium
Blood forming organs
Nasal cavity and larynx
Liver
Important point:
Occupational breast cancer is very rare and is due to ionizing radiation and ethylene oxide
Q-128. Endemic ascites is associated with the following
a) Pyrrolizidine
b) Aflatoxin
c) Sanguinarine
d) Beta oxalyl-amino alanine (BOAA)
Answer: Pyrrolizidine
Explanation:
Food born diseases and toxins:
Lathyrism- Beta Oxatyl Amino Alanine found in Lathyrus sativa
Epidemic dropsy- Sanguinarine found in Argemone oil
Epidemic ascites: Pyrrolizidine alkaloid in Crotalaria.
Q-129. Which of the following is an example of disability limitation?
a) Reducing occurrence of polio by immunization
b) Arranging for schooling of child suffering from PRPP
c) Resting affected limbs in neutral position
d) Providing calipers for walking
Answer: Resting affected limbs in neutral position
Explanation:
Disability limitation:
Mode of intervention used if the patient presents in late pathogenic phase. The objective is to prevent the transition of the disease process from impairment to handicap.
Important points:
Reducing occurrence of polio by immunization – Specific protection
Resting affected limbs in neutral position – Disability limitation
Arranging for schooling of child suffering from PRPP and providing calipers for walking – Rehabilitation
Q-130. Specificity of a screening test measures
a) True positives
b) False positives
c) False negatives
d) True negatives
Answer: True negatives
Explanation:
Sensitivity is the ability of a test to correctly classify an individual as ′diseased′.
Specificity is the ability of a test to correctly classify an individual as disease- free.