Cross-Sectional Studies

Question 1

Definition of Cross-Sectional Studies

Answer 1

• Observational studies that capture health/disease and exposure status at the same time.

AKA Prevalence study

Question 2

Why are cross-sectional studies so named?

Answer 2

Because information gathered represents what is occurring at a point in time or time-frame across a large population.

Acquired without regard to exposure or disease/outcome status

Question 3

Who is selected for a cross-sectional study?

Answer 3

Entire population or a subset

Question 4

What does a cross-sectional study focus on?

Answer 4

• focuses simultaneously on disease & population characteristics, including exposures, health status,…
• Seeks associations
• Generates and tests hypotheses
• by repetition in different time periods

Question 5

What are the two cross-sectional approaches?

Answer 5

• Collect data on each member of the population

- Take a sample of the population & draw inferences to the remainder

Question 6

What is a probability sample?

Answer 6

Every element in the population has a known probability of being included in sample

Question 7

What are some examples of probability sampling schemes?

Answer 7

• Simple Random sampling
• Systematic Random sampling
• Stratified Simple Random sampling
• Stratified Disproportionate Random sampling
• Multi-Stage Random sampling
• Cluster Multi-Stage Random sampling

Question 8

Simple Random Sampling

Answer 8

• Assign random sampling, then take randomly-selected number to get desired sample size
• Assign random numbers, then sequentially-list numbers and take desired sample size from top of numbers

Question 9

Systemic Random Sampling

Answer 9

• Assign random numbers, then randomly sort the numbers, select the 1st or last number and then every Nth number from there

Question 10

Stratified Simple Random Sampling

Answer 10

Stratify by desired characteristic, then use Simple Random sampling to select desired sample size

Question 11

Stratified Disproportionate Random Sampling

Answer 11

• disproportionately utilizes stratified sample when baseline population is not at the desired proportional percentage to the referent population
• stratified sample ‘weighted’ to return sample population back to baseline pop

Question 12

Multistage Random Sampling

Answer 12

Uses simple random sampling at multiple staged towards patient selection

Question 13

Cluster Multistage Random Sampling

Answer 13

Same as multistage random sampling but all elements clustered together or selected for inclusion

Question 14

Non-probability sampling schemes

Answer 14

• Quasis-systematic or Convenience samples

Question 15

Quasi-Systematic or Convenience samples

Answer 15

Decide on what fraction of population is to be samples and how they will be sampled.

Eg. All persons with last name A-H

Question 16

What are the two common broad approaches to collection of study data/information?

Answer 16

• questionnaires/surveys

- physical assessments

Question 17

What are the advantages of cross-sectional studies?

Answer 17

• Quicker & easier for the researcher when using data already collected
• Less expensive for researcher than any form of prospective study
• Can be analyzed like a Case-Control or Cohort study
• Useful for estimating prevalence rates
• Useful for answering research questions about a myriad of exposure and diseases

Question 18

What are the disadvantages for Cross-Sectional Studies?

Answer 18

• Prevalent cases may represent survivors
• Difficult to generate incidence rates
• Problems in determining temporal relationship of presumed cause & effect

Question 19

National Health and Nutrition Examination Survey (NHANES)

Answer 19

Assesses the health & nutritional status of adults & children

• Combines interviews & physical examples
• Interviews include demographic, socioeconomic, dietary, & health-related questions
• Examination component consists of medical, dental, physiological measurements and lab tests

Question 20

National Health Interview Survey (NHIS)

Answer 20

• Principle source of information on health of the civilian, non-institutionalized population
• Data are collected through a personal household interview
• Consists of a core set of questions that remain largely unchanged & a set of supplements used to respond to public health data need as they arise

Question 21

Ambulatory Health Care Data (NAMCS)

Answer 21

• Provides reliable information about the provision and use of ambulatory medical care services in the US.
• Based on a sample of visits to non-federal, office-based, physicians primarily engaged in direct patient care

Question 22

National Hospital Care Survey (NHCS)

Answer 22

• A combined national survey designed to describe national patterns of healthcare delivery in non-federal hospital-based settings

Question 23

Behavioral Risk Factor Surveillance System

Answer 23

• State-based system of telephone surveys that collects info on health risk behaviors, preventative health practices, and health care access primarily related to chronic disease and injury