Biostatistics I

Question 1

All people in a defined geographical area (e.g., Montgomery county, VA) or with certain defined characteristics (e.g., age>65 years & having a thyroid nodule).

Answer 1

population

Question 2

Why to define a population?

Answer 2

We know the group of individuals about whom a statement is made.

We could get some clues on how to get a sample.

Question 3

How to determine a population?

Answer 3

from research question

available resources

Question 4

We know the group of individuals about whom a statement is made.
We could get some clues on how to get a sample.

Answer 4

Sample

Question 5

why use a sample?

Answer 5

less costly
more quick and timely
reliable

Question 6

what is the most important criterion for a sample?

Answer 6

representative of the population

Question 7

a numerical summary of a population?

Answer 7

parameter

Question 8

a numerical summary of sample

Answer 8

statistic

Question 9

Example 1: the average age of all adults living in Blacksburg (μ)
Example 2: the proportion of adults with Type II diabetes living in Blacksburg (p)

parameter or statistic

Answer 9

parameter

Question 10

Example 1: the average age of the 30 samples (𝑥̅)
Example 2: the proportion of Type II diabetes patients in the sample (𝑝̂)

parameter or statistic

Answer 10

statistic

Question 11

Deals with summarizing data from a sample via graphical or numerical approaches

Answer 11

descriptive statistics

Question 12

Refers to making decisions and/or predictions about a population (parameter) based on a sample (statistic)

Answer 12

inferential statistics

Question 13

Examples:
Histogram
Scatterplot
Mean/Median/Mode

Answer 13

descriptive statistics

Question 14

Examples:
Confidence Interval
Hypothesis Testing

Answer 14

inferential statistics

Question 15

inferential statistics are related to inferences about?

Answer 15

population parameters

Question 16

a sample in which every unit in the population has a fixed and known or equal chance of being selected.

what does this allow?

Answer 16

random sample

allows powerful inferences about the population without having to observe the entire population

Question 17

what are the types of sampling strategies?

what are the types of these?

Answer 17

probability sampling

non probability sampling

simple random, systemic, stratified, cluster (involves random selection and gold standard for generalizability)
*probability sampling

convenience sampling and quota sampling
*non-probability sampling

Question 18

Every member of the population has an equal chance of being selected

Answer 18

Probability Sampling _ Simple Random Sampling

Question 19

It is a sample that is selected by a predetermined periodic process

Answer 19

Probability Sampling _ Systematic Sampling

Question 20

When known categories (strata) exist in a population, and a simple random sample can be taken from each of these “strata.”

Answer 20

Probability Sampling _ Stratified Sampling

Question 21

It is a random sample of natural groupings (clusters) of individuals in the population.

Answer 21

Probability Sampling _ Cluster Sampling

Question 22

Get a list of all the people in Blacksburg, put their names or ID in a drawer, and randomly pick a number of people (nowadays people use random number generator).

Answer 22

Probability Sampling _ Simple Random Sampling

Question 23

patient satisfaction with service at a clinic

Answer 23

Probability Sampling _ Systematic Sampling

Question 24

Given the previous knowledge, the effectiveness of flu vaccine differs in terms of age. Divide the whole population into different age groups (e.g. 0-17, 18-60, 60+), and take simple random samples from each group.

Answer 24

Probability Sampling _ Stratified Sampling

Question 25

phone interview of lung cluster patients

Answer 25

Probability Sampling _ Cluster Sampling

Question 26

within stratum between strata to increase precision and representation

Answer 26

Probability Sampling _ Stratified Sampling

Question 27

between clusters within cluster to reduce cost and improve efficiency

Answer 27

Probability Sampling _ Cluster Sampling

Question 28

A sample that is selected in a convenient way that introduces a high risk of biasedness.

Answer 28

Non-Probability Sampling _ Convenience Sampling

Question 29

Collect info from all VCOM GCP students.

Answer 29

Non-Probability Sampling _ Convenience Sampling

Question 30

what type of sampling is the following? Steps: Break the whole population into strata based on certain characteristics: e.g. age, gender. Determine the quota for each stratum. Sampling from each stratum until the quota is reached. Notes: Number of subjects (quota) for each stratum is fixed. Subjects from different strata are as heterogeneous as possible. It differs from stratified sampling in the way samples are drawn within each stratum. It is quicker and easier to carry out.

Answer 30

Non-Probability Sampling _ Quota Sampling

Question 31

what is the purpose of research questions?

Answer 31

What questions will the study address?

Question 32

what is the purpose of background and significance?

Answer 32

Why are these questions important?

Question 33

what is the purpose of design, like: time frame research design

Answer 33

How is the study structured?

Question 34

what is the purpose of subjects, like: selection criteria sampling design

Answer 34

Who are the subjects and how will they be selected?

Question 35

what is the purpose of variables: Predictor variables Outcome variables Confounding variables

Answer 35

What measurements will be made?

Question 36

what is the purpose of Statistical Issues, like: Hypotheses Sample size Analytic approach

Answer 36

How large is the study and how will it be analyzed?

Question 37

what is the overall research goal and general question?

Answer 37

concrete and researchable questions Example: General concern: Should people eat more fish? Specific questions: How often do Americans eat fish? Does eating more fish lower the risk of cardiovascular disease? Is there a risk of mercury toxicity from increasing fish intake in older adults? Do fish oil supplements have the same effects on cardiovascular disease as dietary fish? Which fish oil supplements don’t make you breath smell like fish?

Question 38

a good research question should pass the what test?

Answer 38

so what test, getting the answer should contribute to our state of knowledge

Question 39

what are the five essential characteristics of good research?

Answer 39

``` Feasible Interesting Novel Ethical Relevant ```

Question 40

Describes some interesting or intriguing observations that occurred for a small number of patients

Answer 40

Case series study

Question 41

A group examined at one point in time (e.g., survey)

Answer 41

Cross-sectional study

Question 42

Two groups selected based on presence or absence of an outcome

Answer 42

Case-control study

Question 43

Groups of subjects identified at the beginning and followed over time (retrospective cohort study)

Answer 43

Cohort study (Retrospective and Prospective)

Question 44

Two groups (control and experimental) created by a random assignment

Answer 44

Randomized controlled trial (RCT)

Question 45

explore the lay of the land and lead to generation of research hypotheses.

Answer 45

Descriptive observational studies

Question 46

test one or more predetermined hypotheses about association between exposure and outcome variables.

Answer 46

Analytical observational studies

Question 47

test one or more predetermined hypotheses about association between exposure and outcome variables.

Answer 47

Experimental studies

Question 48

The investigator goes through the medical records of several patients who has been taking fish oil supplements for the past year, and notices their current coronary calcium scores are lower than those from one year ago.

Answer 48

Case Series Study

Question 49

The researcher interviews a group of subjects about current and past history of fish intake and correlates results with history of coronary heart disease (CHD) and current coronary calcium score.

Answer 49

Cross-Sectional Study

Question 50

The researcher examines a group of patients with coronary heart disease (CHD) (the “cases”) and compares them with a group who do not have CHD (the “controls”), asking about past fish intake.

Answer 50

Case-Control Study

Question 51

The investigator measures fish intake in a group of subjects at baseline and periodically examines them at follow-up visits to see if those who eat more fish have fewer coronary heart disease (CHD) events.

Answer 51

Cohort Study

Question 52

The investigator randomly assigns subjects to receive a fish oil supplement or a placebo that is identical in appearance, then follows both groups for several years to observe the incidence of CHD.

Answer 52

Randomized Controlled Trial (RCT)