24-25 Cross Sectional Studies Flashcards
Describe cross sectional studies.
observational, descriptive/analytical studies that examine relationships of health/disease to other variables of interest at the same time
studies all of persons with the variables of interest
defines the geographical boundary for the study
studies disease and risk factor patterns over a specified time period
What is another name for cross sectional studies?
Prevalence studies
Why is it called a cross sectional study?
because information gathered represents what is occurring at a point in time or time-frame a-cross a large population
Is a cross sectional study data a snap shot or continuous?
snap shot
What does cross sectional studies focus on?
simultaneously focuses on disease and population characteristics, including exposures, health status, health-care utilization, etc. depending on study purpose
What functions do cross sectional studies do?
seeks association
generates and tests hypotheses
by repetition in different time periods, can be used to measure change/trends
True or False, most cross sectional studies are surveys of or databases related to different aspects of US population.
True
What are the advantages of cross sectional studies?
fairly quick and easy to perform for the researcher using the data
- data already collected and deidentified
What are cross sectional studies useful for?
determining prevalence of disease and risk factors across the population (or a sample of them)
measuring current health status and planning for health services across the population (or a sample of them)
evaluating differences in sub-groups within the population (at a given time)
What are the disadvantages of cross sectional studies?
prevalent cases may represent survivors
- may be biased in representing people still alive
difficult to study disease of low frequency
- snap shot may not have collected it
problems in determining temporal relationship of a presumed cause and effect
- no temporality you can build; don’t know which came first chicken or egg;
List the 2 cross sectional approaches.
- collect data on each member of the population
2. take a sample of the population and draw inferences to the remainder
When is the first cross sectional approach mostly utilized?
city/state level evaluation
When is the second cross sectional approach mostly utilized?
US (national) level
Describe probability samples of cross sectional sampling schemes.
every element in the population has a known probability of being included in sample
True or false, probability samples are NOT the most common type of sampling scheme.
False, it IS the most common
When are probability samples most even?
when you use a multi-probability, multi-stage selection
List and describe the types of probability samples of cross sectional sampling schemes.
Simple random
- obtain a list of population names - assign numbers to names and use random number generator to select samples
Stratified random
- mutually exclusive strata - age or socioeconomic groups
- divide population into relevant subgroups
- take simple random sample from each subgroup
- some studies over sample certain subgroups such as minorities
List 2 categories of sampling schemes of cross sectional studies.
Probability samples and Systematic (Convienence) samples
Describe systematic samples of cross sectional sampling schemes.
decide on what fraction of population is to be sampled and how they will be sampled
List and describe the 2 approaches to collection of new information in cross sectional studies.
Questionnaire/Surveys
- either directly from patients /caregivers or their medical records
Physical assessments
- great for assessing health/disease in similar population as time changes
From what perspective does NHANES collection data/information?
Assess the health and nutritional status of adults and children
- Combines interviews and physical examinations - interviews include demographic, socioeconomic, dietary, and health-related questions
Survey sample is selected to represent the US population of all ages
- over sample persons greater or equal to 60 years old, Blacks/African Americans and Hispanics
From what perspective does NHIS collection data/information?
Principle source of information on health of the civilian, non-instutionalized population
- survey sample is selected to represent the US population of all ages - has central role in other surveys such as the National survey of Family Growth (NSFG) and the NAMCS/NHCS
From what perspective does NAMCS collection data/information?
A national survey designed to meet the need for objective, 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
From what perspective does NHCS collection data/information?
A combined national survey designed to describe national patterns of healthcare delivery in non-federal hospitals-based settings, including:
- discharges from inpatient departments and institutions, and visits to ER, outpatient departments, and ambulatory surgery centers
integrates 3 cross-sectional surveys:
- National Hospital Discharge Survey (NHDS) - National Hospital Ambulatory Medical Care Survey (NHAMCS) - Drug-Abuse Warning Network (DAWN)
From what perspective does BRFSS collection data/information?
A state-based system of telephone health surveys that collects information on health risk behaviors, preventative health practices, and health care access primarily related to chronic disease and injury
- monthly data collection in all 50 states, DC, Puerto Rico, US Virgin Islands, and Guam - > 500,000 adults (equal or older than 18) are interviewed by telephone - Youth BRFSS conducted by questionnaire in schools
