Que. 1. What do you mean by term population at risk?

Ans. 1. It is the proportion of population that is susceptible to a disease. It can be defined on the basis of demographic or environmental factors.

Que. 2. What do you mean by point prevalence?

Ans. 2. It measures the frequency of disease at a given point in time. It applies when the data has been collected at one point in time. 

Point prevalence = C/N

Where C is the number of observed cases at time t & N is population size at time t.

Que. 3. What do you mean by period prevalence?

Ans. 3. It measures the frequency of disease over some time. It applies when the data has been collected over a period of time.

Period Prevalence = C+I /N

Where C is the number of observed cases at the beginning of the time period, I is the no. of incident cases that develop during the time period & N is the Size of the population for the same time period.

Que. 4. What are the factors that influence the prevalence?

Ans. 4. The factors that influence the prevalence are – 

1.     Number of new cases
2.     Duration of illnesses

•       If the disease is short, prevalence is reduced.
•       If the disease is long, prevalence is increased.

Que. 5. What are the uses of the prevalence data?

Ans. 5. Uses of prevalence data are as follows – 

1.     Study chronic diseases
2.     Assess health care needs
3.     Planning health services
4.     Measure occurrence of conditions with gradual onset.

Que. 6. What do you mean by incidence?

Ans. 6. It is the number of new cases of a given disease or health condition in a given period in a specified population. Incidence measures the rapidity with which new cases are occurring. It can be expressed in absolute numbers or in terms of cumulative incidence or incidence density.

Que. 7. What is the other name of incidence density?

Ans. 7. Incidence rate.

Que. 8. What is the other name of cumulative incidence?

Ans. 8. Attack rate.

Que. 9. How will you calculate cumulative incidence (CI)?

Ans. 9. CI = No. of new cases/Population at risk at the beginning * 1000 or 10000 or 1 lakh

Assumes that the entire population at risk at the beginning was followed-up for the time- period of observation.

Que. 10. How will you calculate the incidence rate?

Ans. 10. Incidence rate = No. of new cases/Total person time of observation* 1000 or 10000 or 1 lakh.

Que. 11. What are the uses of incidence data?

Ans. 11. Following are the uses of the incidence data – 

1.     Describe trends in disease
2.     Evaluate the impact of primary preventive programs.

Que. 12. What is the relation between prevalence and incidence?

Ans. 12. Prevalence (P) = Incidence (I) * duration (D).

Que. 13. What do you mean by case fatality rate?

Ans. 13. It is the ratio of numbers of deaths from a disease to the no. of cases due to that disease. Case fatality rate reflects severity of the disease.

Que. 14. What are the types of the descriptive studies?

Ans. 14. The types of descriptive studies are as follows – 

1.     Case report
2.     Case series
3.     Ecological studies
4.     Cross-sectional study

Que. 15. What do you mean by case reports?

Ans. 15. Case reports include detailed presentation of a single case of new or unfamiliar diseases or with rare manifestations. Case reports may be used to generate hypothesis regarding patho-physiological mechanism.

Que. 16. What do you mean by case series?

Ans. 16. It is the study of large group of patients (i.e. >10) with a particular disease.

Que. 17. What are the advantages of case series?

Ans. 17. The advantages of case series are – 

1.     Larger number of cases may allow the investigator to assess the play of chance.
2.     It is a common way of delineating the clinical pictures of a disease.

Que. 18. What is the disadvantage of case series?

Ans. 18. Do not have a comparison group.

Que. 19. What is the unit of study or analysis in an ecological study?

Ans. 19. Group or population. No individual level information is gathered on the distribution of exposure & disease.

Que. 20. What does an ecological study relate?

Ans. 20. It relates whether populations with high rates of the disease also have high frequency of the suspected exposure.

Que. 21. What is the unit of observation or analysis in a cross-sectional study?

Ans. 21. The individual.

Que. 22. What do you mean by cross-sectional study?

Ans. 22. It is the observation of a cross-section of a population at a single point in time. Unit of observation or analysis being an individual. It collects information about disease burden, therefore also called PREVALENCE STUDIES. Observation is made for the presence of one or more outcomes or one or more exposures.

Que. 23. What are the uses of cross-sectional study?

Ans. 23. Followings are the uses of cross-sectional study – 

1.     Estimates prevalence of disease or their risk factors
2.     Study distribution of health problem by time, place and person
3.     Sets priorities for disease control
4.     Generates hypothesis 
5.     Estimates evolving trends of health problems.

Que. 24. What are the advantages of cross-sectional study?

Ans. 24. The advantages of cross-sectional study are as follows – 

1.     Fairly quick & easy to perform.
2.     Less expensive.

Que. 25. What are the limitations of cross-sectional study?

Ans. 25. The limitations of cross-sectional study are as follows – 

1.     Not useful to study disease etiology.
2.     Not suitable for the study of rare diseases
3.     Identifies both new and old cases.

Que. 26. In which epidemiological study, exposure and outcome are examined at the same time?

Ans. 26. Cross-sectional study.

Que. 27. Which epidemiological study is useful to measure the burden or magnitude of a disease or risk factor?

Ans. 27. Cross-sectional study.

Que. 28. Which epidemiological study design does not employ comparison group to answer the primary study objectives?

Ans. 28. Cross-sectional study.

Que. 29. Risk factors of the study cannot be assessed by which epidemiological study?

Ans. 29. Descriptive study.

Que. 30. Which study design does provide group exposure & group response/outcome without knowing the individual exposure and response for a specific health problem?

Ans. 30. Ecological study.

Que. 31. Which type of study is a population census?

Ans. 31. Cross-sectional survey.

Que. 32. Which are the characteristics of analytical studies?

Ans. 32. The characteristics of analytical studies are – 

1.     Investigator does not assign the exposure
2.     There is invariably a comparison group.

Que. 33. What do you mean by Cohort?

Ans. 33. Group of people sharing common characteristics called cohort e.g. birth cohort.

Que. 34. What are the types of cohort study?

Ans. 44. The types of cohort study are as follows – 

1.     Prospective cohort study
2.     Retrospective cohort study
3.     Ambispective cohort study

Que. 35. What are the elements of cohort study?

Ans. 35. The elements of cohort study are as follows – 

1.     Selection of study populations
2.     Gathering baseline information
3.     Follow up
4.     Analysis

Que. 36. What are the choices of comparison group in cohort study?

Ans. 36. The choices of comparison group in cohort study are as follows – 

1.     Internal comparison group e.g. unexposed persons in the population
2.     External comparison group when internal comparison group is not available.

Que. 37. How will you calculate Relative Risk?

Ans. 37. RR = Incidence of disease among exposed/ Incidence of disease in unexposed.

                       = (a/a+b) /(c/c+d).

Que. 38. What interpretation will you make if RR <1?

Ans. 38. Incidence in exposed is lower than in unexposed, meaning that exposure is negatively associated with the disease.

Que. 39. What interpretation will you make if RR = 1?

Ans. 39. Incidence in exposed and unexposed is equal, meaning that exposure is not associated with the disease.

Que. 40. What interpretation will you make if RR >1?

Ans. 40. Incidence in exposed is greater than that in unexposed, meaning that exposure is positively associated with the disease.

Que. 41. How is the progression of a cohort study?

Ans. 41. From Cause/exposure to effect or outcome.

Que. 42. What are the strengths of cohort study?

Ans. 42. Followings are the strength of cohort study – 

1.     Incidence can be calculated
2.     Examines multiple outcomes for a single exposure
3.     Clarity of temporal sequence
4.     Good for investigating rare exposures.

Que. 43. What are the weaknesses of cohort study?

Ans. 43. Followings are the weaknesses of a cohort study – 

1.     Expensive & time consuming
2.     Not good for rare disease
3.     Not good for diseases with a long latency
4.     Differential loss to follow up can introduce bias.

Que. 44. How is the progression of a case control study?

Ans. 44. From effect/outcome to cause/exposure. It is a backward study.

Que. 45. What are the elements of a case control study?

Ans. 45. The elements of a case control study are – 

•       Selection of cases
•       Selection of controls
•       Information on exposure
•       Analysis.

Que. 46. What are the strengths of a case control study?

Ans. 46. Following are the strengths of a case control study – 

•       Good for examining rare diseases or diseases with a long latency
•       Quick to conduct and inexpensive
•       Requires comparatively few subjects
•       Multiple exposures or risk factors can be examined.

Que. 47. What are the weaknesses of case control study?

Ans. 47. Following are the weaknesses of case control study – 

1.     Susceptible to recall bias
2.     Selection of an appropriate comparison group may be difficult

•       Relates of disease in exposed and unexposed individuals cannot be determined.

Que. 48. In which epidemiological studies, exposure is not assigned by the investigator?

Ans. 48. Descriptive & Analytical studies.

Que. 49. In which epidemiological studies, exposure is assigned by the investigator?

Ans. 49. Experimental study.

Que. 50. What do you mean by randomized controlled clinical trials?

Ans. 50. A randomized controlled clinical trial is a planned experiment designed to assess the efficacy of prophylactic/diagnostic/therapeutic agents, devices, regimens, procedures etc. applied to human subject.

It essentially involves comparing the outcomes in a group of patients treated with a test treatment with those observed in a comparable group of patients receiving a control treatment where patients in both groups are enrolled in a prospective study treated or exposed to intervention and followed over same period.

Que. 51. What are the objectives of clinical trials?

Ans. 51. These are generally conducted to evaluate new forms of therapy, diagnostic procedures or preventive methods.

Que. 52. Which is the heart of the randomized controlled clinical trials?

Ans. 52. Randomization. 

Que. 53. What do you mean by randomization?

Ans. 53. Randomization ensures that participants have an equal chance to be assigned to one of two or more groups.

Que. 54. Mention the types of blinding.

Ans. 54. The types of blinding are – 

1.     Participants (Single blinding)
2.     Participants & Investigator (double blinding) & 
3.     Participants, Investigators & Analysts (Triple blinding).

Que. 55. What are the objectives of phase I to phase IV clinical trials?

Ans. 55. The objectives of phase I-IV clinical trials are as follows – 

Que. 56. What are the sample size & participants of phase I – IV clinical trials?

Ans. 56. The sample size & participants of phase I-IV clinical trials are as follows – 

Que. 57. What are the advantages of RCTs?

Ans. 57. Following are the advantages of RCTs – 

1.     The only effective method to control selection bias
2.     Controls confounding bias without adjustment
3.     Facilitate effective blinding
4.     Maintains advantages of cohort studies.

Que. 58. What are the disadvantages of RCTs?

Ans. 58. Following are the disadvantages of RCTs – 

1.     Complex & expensive
2.     Lack representativeness – volunteers differ from population of interest
3.     Immense ethical challenge.

Que. 59. What do you mean by Placebo?

Ans. 59. A pharmacologically inactive agent that the investigators administer to participants in control group of a trial is called Placebo.

Que. 60. What is the purpose of double blinding in a RCT?

Ans. 60. To avoid observer & participants bias.

Que. 61. What do you mean by external validity?

Ans. 61. Obtaining an estimate that is generalizable to relevant study population in an epidemiological study is called external validity.

Que. 62. What do you understand by term bias?

Ans. 62. Any process that tends to produce results that depart systemically from the values in an epidemiological study.

Que. 63. Which type of bias does result when systematic selection of more number of exposed participants with high risk of outcome in a cohort study will be done?

Ans. 63. Selection bias.

Que. 64. What do you mean by confounding?

Ans. 64. The effect of the exposure of interest on the outcome is distorted because of the effect of extraneous factors that are related to both the exposure and outcome. This phenomenon is called confounding.

Que. 65. Biases can occur during which stage of epidemiological study?

Ans. 65. At any stage from study design to analysis.

Que. 66. How will you minimize the information bias?

Ans. 66. The information bias may be minimized by – 

•       Precise operational definitions of variables
•       Detailed measurement protocols
•       Repeated measurement on key variables
•       Training, certification & recertification
•       Data audits
•       Data cleaning
•       Re-running all analysis prior to all publication.

Que. 67. What do you mean by Chance?

Ans. 67. Variability in estimation due to unknown or uncontrollable factors is called chance.

Que. 68. Which are the methods used to alleviate confounding during data analysis in an epidemiological study?

Ans. 68. Stratification & Multivariate analysis.

Que. 69. What do you mean by Internal Validity?

Ans. 69. Obtaining an accurate estimate of disease frequency and effect of exposure on health outcome in study population is known as Internal Validity.

Que. 70. Which type of biases are prevented by blinding in an epidemiological study?

Ans. 70. Selection bias & Information bias.

Que. 71. What do you mean by term validity?

Ans. 71. The ability of a tool to correctly measure what it is supposed to measure is called validity.

Que. 72. Which methods are used to address for known confounders at the designing stage of a study?

Ans. 72. Restriction, Matching & Randomization.

Que. 73. What do you mean by term prevarication?

Ans. 73. Systematic distortion of the truth by study subject is called prevarication.

Que. 74. What are the effects of confounding in epidemiological studies?

Ans. 74. The effects of confounding are – 

1.     May simulate an association that does not exist
2.     May hide an association that does exist
3.     May change the direction of an effect
4.     May increase or decrease the strength of association.

Que. 75. How will you deal with selection bias during designing stage of a study?

Ans. 75. Selection bias during designing stage of a study can be dealt with – 

1.     Use of incident cases, not prevalent cases
2.     In Case Control studies – 

•       Use population based design
•       Apply same eligibility criteria for selecting cases and controls
•       Both cases and controls undergo the same diagnostic procedures & intensity of disease surveillance.

Que. 76. How will you deal with selection bias during data collection stage of the study?

Ans. 76. The selection bias during data collection stage of the study may be dealt with – 

1.     Minimize the non-response, non-participation and loss to follow up (Cohort studies)
2.     Keep a record on all losses and collect baseline data on them.
3.     Make sure that diagnosis of disease is not affected by exposure status (Blinding).

Que. 77. How will you deal with selection bias during analysis stage of study?

Ans. 77. The selection bias during analysis stage of the study may be dealt with – 

1.     Compare non-responders/dropouts with responders/non-dropouts with respect to baseline variables
2.     Use study results and external information to deduce the direction of biases and assess magnitude of biases.

Que. 78. What are the important features of Random Error?

Ans. 78. In random error,

1.     No sample is likely to give us results which are exactly the same as the truth in local population.
2.     No two samples drawn from the same population are likely to give us the same results
3.     It will not occur if we study the entire population.

Que. 79. What do you mean by Precision?

Ans. 79. The ability of a measurement process to diagnose correctly as positive those who really have the disease.

Que. 80. What is the other name of randomization?

Ans. 80. Random allocation.

Que. 81. In which type of epidemiological study, loss to follow up or attrition is a problem?

Ans. 81. Cohort studies.

Que. 82. In which type of study design, it is sometimes difficult to establish temporal association?

Ans. 82. Cross-sectional study.

Que. 83. Which is the most likely reason for failure to establish a cause –effect relationship with small sample size?

Ans. 83. Beta error or type II error.

Que. 84. Which is indicative of the strength of association in a cause effect relationship?

Ans. 84. The magnitude of OR/RR.

Que. 85. If OR/RR=1, what does it indicate?

Ans. 85. There is no cause effect relationship.

Que. 86. What do you mean by Berkson’s bias?

Ans. 86. This is the bias due to different rates of admission to hospitals for those who have more than one disease.

Que. 87. What does cross sectional study give as a measure of risk?

Ans. 87. Prevalence odds ratio.

Que. 88. What are the disadvantages of cross-sectional vs. case control study?

Ans. 88. Huge logistics & large sample size.

Que. 89. What is the tool for the control of confounder in experimental design?

Ans. 89. Randomization.

Que. 90. What is the measure of risk in a cohort study?

Ans. 90. Relative risk.

Que. 91. Prevalence will affect the ______________________ of a test?

Ans. 91. Predictive value.

Que. 92. What is plotted along the Y axis in ROC curve?

Ans. 92. Sensitivity.

Que. 93. While analyzing data, what is the purpose of allocation into similar groups?

Ans. 93. To ensure comparability.

Que. 94. Numerator is not a part of denominator in ————-.

Ans. 94. Ratio.

Que. 95. What is the denominator in crude death rate?

Ans. 95. Mid-year population.

Que. 96. What is the outcome of longitudinal studies?

Ans. 96. Can find out incidence of disease.

Que. 97. In which insect, trans-ovarian transmission of infection occurs?

Ans. 97. Ticks.

Que. 98. What do you mean by term Medical Audit?

Ans. 98. Retrospective study of case sheets (hospital data) & evaluation of medical data is called Medical Audit.

Que. 99. Which study does give scientific proof of an etiological factor?

Ans. 99. Randomized clinical trial.

Que. 100. Which rate does tell about the communicability of a disease?

Ans. 100. Secondary Attack Rate.

Que. 101. What does serial interval measures?

Ans. 101. Incubation period of disease.

Que. 102. What is the best method to compare vital statistics of two population?

Ans. 102. Age standardized death rate.

Que. 103. In which disease, Herd immunity is not important?

Ans. 103. Tetanus.

Que. 104. What is an epidemic?

Ans. 104. An epidemic is occurrence of cases in excess of normal expectations.

Que. 105. What do you mean by Serial Interval?

Ans. 105. It is the time interval between the on-set of Primary & Secondary case.

Que. 106. Which epidemiological study is used to confirm or refute an etiological hypothesis?

Ans. 106. Experimental Epidemiology or study.

Que. 107. What is the means to study the association between disease & risk factor in a case control study?

Ans. 107. ODDS RATIO.

Que. 108. Bhopal gas tragedy is an example of which epidemic?

Ans. 108. Point source Epidemic.

Que. 109. What is the first step in investigation of Epidemic?

Ans. 109. Verification of Diagnosis.

Que. 110. What is the main drawback of calculating incidence of disease using hospital records?

Ans. 110. Denominator is not well defined.

Que. 111. What do you call an epidemic occurring every 5 years?

Ans. 111. Cyclical trend.

Que. 112. When launching a study, many respondents are invited, some of whom fail to come. What type of Bias is it?

Ans. 112. Volunteer Bias.

Que. 113. How will you express attributable risk?

Ans. 113. In percentage.

Que. 114. When disease frequency is measured over a period of decades, what will you call this?

Ans. 114. Secular trend.

Que. 115. How will you define Epidemiology?

Ans. 115. “The study of the distribution & determinants of health related states or events in specified populations and the application of this study to the control of health problems.”

Que. 116. How will you calculate standardized mortality ratio?

Ans. 116. Observed Deaths/ Expected Deaths * 100 = SMR.

Que. 117. Prevalence rate is actually a rate or ratio?

Ans. 117. Ratio.

Que. 118. What do you mean by term “Epidemic Curve”?

Ans. 118. A graph of the time distribution of epidemic cases is called the EPIDEMIC CURVE.

Que. 119. What does an epidemic curve suggest?

Ans. 119. It suggests – 

1. A)   A time relationship with exposure to a suspected source.
2. B)   A cyclical or seasonal pattern suggestive of a particular infection &
3. C)   Whether common source or propagated spread of the disease.

Que. 120. What are the two ways for carrying out Migration studies?

Ans.  120. Two ways are – 

1. A)   Comparison of disease & death rate for migrants with those of their kilns who have stayed at home.
2. B)   Comparison of migrants with the local population of host country.

Que. 121. What do you mean by term BIOMODALITY?

Ans. 121. Sometimes there may be two separate peaks instead of one in the age incidence curve of a disease e.g. Hodgkin’s Disease, Leukemia, breast Cancer etc.

Que. 122. What are the uses of Descriptive epidemiology?

Ans. 122. Uses are as follows – 

1. A)   Provides the information about magnitude of disease problem & types of disease problem in the community.
2. B)   Provides clues to disease etiology & helps in the formation of etiological hypothesis.
3. C)   Provides data for monitoring, evaluation, planning & organizing Preventive & curative services.
4. D)   Helps in research work by describing variations in disease occurrence by time, place & person.

Que. 123. How will you define Relative risk?

Ans. 123. Relative Risk (RR) is the ratio of the incidence of disease (or death) among exposed & the incidence among non-exposed.

Que. 124. How will you define Attributable risk?

Ans. 124. Attributable risk (AR) is the difference in incidence rates of disease (death) between an exposed group & non exposed group.

Que. 125. What do you mean by term population attributable risk?

Ans. 125. It is the incidence of the disease (or death) in the total population minus the incidence of disease (or death) among those who were not exposed to the suspected causal factor.

Que. 126. What are the aims of experimental Epidemiology?

Ans. 126. – To provide scientific proof of etiological hypothesis.

–       To provide a method of measuring effectiveness & efficiency of health services & thus to improve the health of the community.

Que. 127. What are the uses of epidemiology?

Ans. 127. The uses are as follows – 

1. a)     To study historically the rise & fall of disease in the population.
2. b)   Community Diagnosis.
3. c)     Planning & evaluation
4. d)   Evaluation of individual’s risk & chances
5. e)   Syndrome identification
6. f)     Completing the natural history of disease
7. g)     Searching for causes & risk factors

Que. 128. What are the uses of epidemiology in health care management?

Ans. 128. The uses are – 

1)    Making a community diagnosis

2)    Planning & evaluation of health services

3)    Developing public health policies

Que. 129. What are the uses of epidemiology in understanding the disease process?

Ans. 129.  The uses are – 

1)    Study of the natural history of disease

2)    Searching for the causes & risk factors for the diseases

3)    Historic study of the rise & fall of the diseases

4)    To identify syndromes

Que. 130. What are the uses of epidemiology in public health practice?

Ans. 130. The uses are – 

1)    Investigation of epidemics

2)    Surveillance for diseases

3)    Making projections

4)    Assessing the programs for mass screening for diseases

Que. 131. What are the uses of epidemiology in clinical and preventive practice?

Ans. 131. The uses are – 

1)    Assessing the effectiveness of treatment and preventive modalities

2)    Assessing & study of prognosis

3)    Assessing the effectiveness of diagnostic procedures

4)    Assisting in clinical decision making

Que. 132. What do you mean by quantitative data?

Ans. 132. Data which is collected in terms of mathematical figures e.g. BP, body weight, serum cholesterol etc. It is also known as Numerical data.

Que. 133. What do you mean by qualitative data?

Ans. 133. When information is not recorded in form of numbers but according to certain defined qualities or attributes e.g. Sex – M/F, Blood group – A, B, O, AB etc.

Que. 134. Name the scales that can be used to collect quantitative data.

Ans. 134. The scales are – 

1)    Discrete or Numerical scale

2)    Numerical continuous scale

3)    Numerical ordinal scale

Que. 135. Name the scales that can be used to collect qualitative data.

Ans. 135. The scales are – 

1)    Nominal dichotomous scale

2)    Nominal polychotomous scale

3)    Polychotomous ordinal scale

Que. 136. What does attributable risk tell us?

Ans. 136. It tells us percentage of outcome among the exposed group which is due to exposure. If the exposed people give up their exposure habit, it would result in that much percent reduction of the outcome in the exposed group.

Que. 137. What does population attributable risk tell us?

Ans. 137. If exposure (e.g. Alcohol) is removed from the total population, then it will result in a responsible reduction of the outcome (say IHD) in the total population.

Que. 138. What are the uses of secular trends of a disease or health events?

Ans. 138. The uses are – 

1)    Prediction about future course of the disease

2)    Evaluation of programs

3)    Policy decisions or planning

4)    Conceptualize the hypothesis for the change in incidence of disease

Que. 139. What are the uses of mortality data?

Ans. 139. The uses of mortality data are – 

1)    Policy decision & planning

2)    Evaluation of programs

3)    Monitoring of various related programs

4)    Epidemiological research

Que. 140. Define term endemic.

Ans. 140. Occurrence of disease in a given community in usual or expected frequency.

Que. 141. What do you mean by communicable disease?

Ans. 141. An illness due to a specific infectious agent or its toxic products capable of being transmitted from man to man and from environment to man or from animal to man.

Que. 142. What are the types of randomized controlled trials?

Ans. 142. The types are as follows – 

1)    Clinical control

2)    Preventive trial

3)    Risk factor trial

4)    Cessation experiments

5)    Trial of etiological agents

6)    Evaluation of health services

Que. 143. What do you mean by spurious association?

Ans. 143. Sometimes an observed association between a disease and suspected factor may not be real.

Que. 148. What is the disadvantage of crude death rate?

Ans. 148. Lack comparability for communities with population that differ by age, sex, race etc.

Que. 149. Why case fatality rate is not much useful in chronic diseases?

Ans. 149. As the period from onset to death is long and variable.

Que. 150. Whether case fatality rate is closely related to virulence?

Ans. 150. Yes.

Que. 151. When will you use proportion mortality rate?

Ans. 151. When population data are not available.

Que. 152. What is survival rate?

Ans. 152. Survival rate is a method of describing prognosis in certain diseases e.g. cancers.

Que. 153. Which is the heart of a control trial?

Ans. 153. Randomization.

Que. 154. What does cohort study yield?

Ans. 154. Incidence rate, relative risk & attributable risk.

Suggested Further Readings – 

1)    K. Park; Park’s textbook of Preventive & Social Medicine, 26th edition, 2021

2)    R. Bhalwar; textbook of Public health & Community Medicine, AFMC-WHO, 1st  edition, 2009

3)    Mahajan & Gupta; Textbook of Preventive & Social Medicine; 4th edition

4)    AH Suryakantha; Community Medicine with Recent Advances, 3rd Edition.