Biostatistics & Research Methodology

Biostatistics & Research Methodology

A researcher administers an achievement test to assess & indicate the possible effect of an independent variable in her

Negatively skewed distribution shows long left tail with most scores clustered at high end. In achievement testing, such right-concentration indicates many examinees scored high, implying test was relatively easy, not difficult, requiring discrimination analysis for normalization consideration.

Ref: Gravetter and Wallnau, Statistics for the Behavioral Sciences, 10th Edition, Chapter 2 Frequency Distributions and Skewness, explains negative skew indicates clustering at high scores implying test easiness and need for difficulty analysis, published by Cengage Learning.

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Biostatistics & Research Methodology

A research laboratory examined their data of 100 patients proven to have tuberculosis based on results from sputum cultu

Among 100 culture-proven tuberculosis patients, microscopy detected 40 true positives versus 80 by novel test. True positive rate defines sensitivity. Higher detection demonstrates improved sensitivity of new test, while specificity cannot be judged without non-diseased controls included.

Ref: Gordis Leon, Epidemiology, 5th Edition, Chapter 5 Assessing Validity of Diagnostic Tests, defines sensitivity as proportion of true diseased detected positive and explains improved detection rate comparison between microscopy and novel tuberculosis test, published by Elsevier Saunders.

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Biostatistics & Research Methodology

The pre-test with the questionnaire before conducting a survey is denoted by which of the following term?

Pilot survey or pre-testing involves administering questionnaire to small subset before main study to check clarity, feasibility and reliability. It identifies ambiguous items, estimates time and improves validity, preceding full-scale epidemiological or clinical data collection process.

Ref: Fowler and Cohen, Practical Statistics for Field Biology, 2nd Edition, Chapter 3 Survey Design and Pilot Surveys, describes pre-testing questionnaire through pilot survey to assess comprehension and reliability before main study, published by Wiley Blackwell.

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Biostatistics & Research Methodology

“The percent of total variation in the dependent variable that is explained by the set of independent variables in the s

Coefficient of determination, denoted R-squared, quantifies proportion of total variance in dependent variable explained by independent variables in regression model. Values range zero to one, indicating goodness-of-fit, distinct from covariance, multicollinearity or logistic regression concepts.

Ref: Kleinbaum Kupper Nizam and Rosenberg, Applied Regression Analysis and Other Multivariable Methods, 5th Edition, Chapter 9 Coefficient of Determination, defines R squared as percent of total variation explained by independent variables, published by Cengage Learning.

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Biostatistics & Research Methodology

Which of the following denotes “Five equal groups into which a population can be divided according to the distribution o

Quantiles divide distribution into equal frequency intervals. Quartiles create four groups, deciles ten, percentiles hundred, and quintiles five equal groups each containing twenty percent of population values, useful for income distribution and epidemiological stratification analyses.

Ref: Pagano and Gauvreau, Principles of Biostatistics, 2nd Edition, Chapter 4 Quantiles and Boxplots, defines quintiles as division into five equal groups each containing twenty percent of population distribution for socioeconomic stratification, published by Cengage Learning.

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Biostatistics & Research Methodology

The weight of three persons who participated in a health study were 56, 50 and 47 Kilograms. Calculate the arithmetic we

Arithmetic mean or average equals sum of observations divided by count. Adding weights 56+50+47=153 and dividing by three participants yields 51 kilograms, representing central tendency of weight data in this small health study sample.

Ref: Park's Textbook of Preventive and Social Medicine 26th Edition, Chapter 20 Biostatistics, explains arithmetic mean calculation as sum of observations divided by number of subjects for weight and other health parameters, published by Banarsidas Bhanot Publishers.

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Biostatistics & Research Methodology

A researcher has access to data pertaining to the health expenditure of individuals. If each value of this data series i

Median is positional average resistant to outliers but sensitive to scale transformation. Multiplying every observation by constant multiplies ordered middle value by same factor, preserving rank. Hence median becomes ten times original, maintaining distribution shape proportionally.

Ref: Gupta SC and Kapoor VK, Fundamentals of Mathematical Statistics, 12th Edition, Chapter 3 Measures of Central Tendency, explains effect of scaling data by constant on median preserving order and multiplying positional value, published by Sultan Chand and Sons.

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Biostatistics & Research Methodology

ANOVA is a statistical technique, which is used to test which one of the following?

Analysis of Variance partitions total variability into between-group and within-group components. By comparing variance estimates via F-ratio, it tests whether group variances originate from same population, essentially assessing homogeneity of variances as stated in this key.

Ref: Fisher R A, Statistical Methods for Research Workers, 14th Edition, Chapter 8 Analysis of Variance, describes ANOVA partitioning total variance into between and within components and using F-ratio to test equality of variances, published by Oliver and Boyd.

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Biostatistics & Research Methodology

The value of variance for the number of COVID cases due to non-adherence to COVID appropriate behaviour is 64. Calculate

Variance measures squared deviations from mean, while standard deviation equals its positive square root representing dispersion in original units. Given variance 64, standard deviation = √64 = 8, useful for interpreting spread of COVID case counts.

Ref: Daniel Wayne, Biostatistics A Foundation for Analysis in the Health Sciences, 11th Edition, Chapter 4 Descriptive Statistics, defines variance as average squared deviation and standard deviation as square root with calculation examples, published by Wiley.

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Biostatistics & Research Methodology

Among the data collected for a clinical study in diabetic patients, which of the following is NOT a scalar variable?

Scalar or quantitative variables possess numeric magnitude like glucose level, insulin units and age. District name denotes categorical, nominal area classification without intrinsic order or numeric value, therefore qualitative, not scalar, unlike other three measurements listed.

Ref: Park's Textbook of Preventive and Social Medicine, 26th Edition by K Park, Chapter 20 Biostatistics and Research Methodology, differentiates quantitative scalar variables such as glucose and age from qualitative nominal variables like district, published by Banarsidas Bhanot.

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Biostatistics & Research Methodology

The Indian Council of Medical Research updated its national ethical guidelines for biomedical and health research involv

Indian Council of Medical Research National Ethical Guidelines for Biomedical and Health Research involving human participants were comprehensively revised and released in 2017, replacing 2006 version. They mandate ethics committees, informed consent and vulnerability protection principles.

Ref: Indian Council of Medical Research, National Ethical Guidelines for Biomedical and Health Research Involving Human Participants, 2017 Edition, Section 1 Introduction, details revision timeline and ethical principles governance, published by ICMR Department of Health Research New Delhi.

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Biostatistics & Research Methodology

While evaluating an investigational new drug, a ‘Phase I study’ is conducted on:

Phase I clinical trials evaluate investigational new drug primarily for safety, tolerability and pharmacokinetics. Conducted on small cohort of 20-100 healthy volunteers under close monitoring, they determine maximum tolerated dose before efficacy testing in patients.

Ref: K D Tripathi, Essentials of Medical Pharmacology, 8th Edition, Chapter 5 Clinical Pharmacology and Drug Development, discusses Phase I studies on healthy volunteers for safety pharmacokinetics and tolerability assessment, published by Jaypee Brothers Medical Publishers.

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