Biostat

Question 1

Biostat

1.Best test to dermine incidence?
2.which is always longitudinal, prospective and analytic?
3.sample frame is must for which sample technique?

Answer 1

Biostat

1.Best test to dermine incidence?-Cohort
2.which is always longitudinal, prospective and analytic?-RCT
3.sample frame is must for which sample technique?simple random sampling

Question 2

1.Gold standard for evaluating new information?

Answer 2

RCT

Question 3

What is equivalant to median?

Answer 3

50th percentile

Question 4

Mean of sqaure deviation of individual value from central value?

Answer 4

Variance

Question 5

Best sampling for small and homogenous group?

Answer 5

Simple random sampling

Question 6

Best random sampling for heterogeneous group?

Answer 6

Stratified Random sampling

Question 7

Best non random sampling for heterogenous group?

Answer 7

Quota sampling

Question 8

Types of research?

Answer 8

1. Quantitative research
2. Qualitative research
3. Basic (pure) research
4. Applied (practical) research
5. Descriptive research
6. Analytical (explanatory) research

Question 9

Types of variable?

Answer 9

Based on characteristics: (Example)

A. Quantitative (numerical): Vary in amount
1. Continuous: In decimal e.g. height, weight
2. Discrete: In integer e.g. family member
B. Qualitative (categorical): Vary in category
1. Nominal: e.g. sex, religion
2. Ordinal: e.g. tumor grading

Question 10

Types of variable based on relationship to each other?

Answer 10

★Independent(Exposure)variable: ex: Cause,exposure,input
যেমন smoking

★ Dependant variable: যেমন Lunng Ca.Depends on smoking.
★Confounding vaiable :Independant কে যে এম্পলিফাই করবে।কিন্তু নিজে করবেনা,সেটাই confounding..

★ Intervening variable:Idependant টা সরাসরি আউটকাম করবে না। কিন্তু অন্য মাধ্যমে করবে।এই অন্য মাধ্যমটাই হলো intervening.. যেমন Salt(independent) HTN(intervening) এর মাধ্যমে HF করে

Question 11

What is study design?

Answer 11

Scientific and ethical method of search to collect valid and reliable data.

Question 12

Types of study?

Answer 12

A. Observational study: (no intervention only observe)
★Descriptive study –
 Case study
 Surveillance
 Census
 Cross sectional study

★Analytical study:
 Case control study
 Cohort study (Strongest)
 Cross sectional study

B. Experimental study (interventional, Do & Observe)
 Clinical trial (study on human)
 RCT (randomized controlled trial)
 Non randomized controlled trial

Question 13

Criteria of retrospective study?

Answer 13

★Moves from outcome to exposure
★Deals with pervious data
★ Backward looking study e.g. history of smoking in lung cancer

Question 14

Criteria of prospective study?

Answer 14

★Moves from exposure to outcome ★Deals with future data
★Forward looking study e.g. clinical outcome of angioplasty in CAD.

Question 15

Criteria of longitudinal study?

Answer 15

★Data collected at more than one point of time
★Follow up given on same study subjects
★Mostly prospective but may be retrospective

Question 16

Criteria of cross sectional study?

Answer 16

Enrolment: a cross section of population (By neither exposure nor outcome)

★ Measures exposure & outcome simultaneously
★ No follow up; only finds what is happening right now

Question 17

Criteria of Case control study?

Answer 17

By outcome; independent of exposure

Features:
★Observational
★retrospective
★analytical

(Polar থেলে p&L বাদ)

Question 18

Criteria of cohort study?

Answer 18

Enrolment: by exposure; all outcome free

★Compare future outcome in two groups
★Features: observational, prospective/retrospective, longitudinal, analytical.(POLAR)

★★★Good for rare exposure.
★★★we can found incidence rate&relative risk

Question 19

Biostat

Q. Negative predictive value affected by….. ?

Answer 19

Prevalence

Question 20

Features of RCT

Answer 20

★Involve human volunteer
★ Interventional
★ Prospective
★longitudinal
★analytical
★Randomized (Essential feature)

Question 21

Blinding (masking): Ignorance about the treatment status of participants..Types?

Answer 21

Single,double and triple

Question 22

Types of Random sampling?

Answer 22

Random (probability or representative) sampling done by lottery or random process

★ Simple random sampling
★ Systematic random sampling
★ Stratified random sampling
★Cluster sampling
★Multi stage sampling (area sampling)
★ Multi phase sampling

Question 23

Examples of Non random sampling?

Answer 23

Non random (non probability or non representative) sampling done without lottery / random process

★ Convenient (accidental) sampling
★ Purposive (judgment) sampling
★ Quota sampling
★Snowball sampling

Question 24

Measures of Location?

Answer 24

➢ Measures of central tendency: Mean, median, mode.
➢ Percentiles
➢ Deciles
➢ Quartiles

Question 25

Use of the measures of central tendency

Answer 25

➢ Quantitative data: Mean, median & mode
➢ Nominal data: Mode
➢ Ordinal data: Median & mode

Question 26

Measures of Dispersion

Answer 26

 Range
 Mean deviation
 Standard deviation
 Variance
 Inter quartile range
 Inter decile range (IDR)
 Coefficient of variation (CV

Question 27

Features of Normal Distribution

Answer 27

★Bell shaped & bilaterally symmetrical ★Mean, median & mode coincide
★ About 50% values above & 50% values below the mean
★ Maximum values lie in the middle around the mean

Question 28

Regarding SD

Answer 28

 Mean ± 1SD covers 68% values
 Mean ± 2SD covers 95% values
 Mean ± 3SD covers 99% values

Question 29

Right Skew Distribution (asymmetric)

Answer 29

 Curve skewed to the right.
 Higher frequency at lower values.
 Lower frequency at higher values e.g. marks of hard examination.

Question 30

Left Skew Distribution (asymmetric)

Answer 30

 Curve skewed to the left
 Higher frequency at higher values
 Lower frequency at lower values

Question 31

Graphs: for quantitative data

Answer 31

 Histogram
 Frequency polygon
 Frequency curve
 Line chart
 Scattered diagram
 Box-plot
 Stem & leaf plot

Question 32

Charts / diagram: for qualitative data

Answer 32

 Simple bar diagram
 Multiple bar diagram
 Component bar diagram
 Pie diagram
 Pictogram
 Map diagram

Question 33

Categories of Test of Hypothesis.

Parametric test:

Answer 33

Parametric test: Quantitative data with normal distribution e.g.

 t-test
 Z-test
 F-test (ANOVA)
 Pearson’s correlation coefficient test

Question 34

Categories of Test of Hypothesis.

Non parametric:

Answer 34

Non parametric test: Qualitative data Quantitative data with skewed distribution e.g.
 Chi-square test
 Proportion test
 Spearman rank correlation test
 Fisher exact test
 Mann-Whitney U test

Question 35

Students ‘t’ Test (unpaired) Preconditions:

Answer 35

 Comparison between two means of two separate groups.
 Quantitative data with normal distribution.
 Unpaired design
 Sample size less than 30

Question 36

Students ‘t’ Test (Paired) Preconditions:

Answer 36

 Comparison between two means of two dependent groups
 Quantitative data with normal distribution
 Paired design

Question 37

Preconditions for ANOVA (F-test)

Answer 37

 Comparison among the means of >2 groups.
 Quantitative data.