Chapter 19 Flashcards
At least four types of populations considered when preparing to collect data. (4) Broadest to smallest
Target population
Source population (sampling frame)
Sample population
Study population
Sampling bias
sample is not representative of the source as a whole
Nonrandom sampling bias occurs when
Each individual does not have an equal chance of being selected for the sample population
Simple random sampling
Each person has an equal chance of being selected
Systemic sampling
sampling starts with a random person and then everyone the nth number after that person is selected
Stratified sampling
Simple random samples selected from each of several strata
Cluster sampling
An are is divided into geographical clusters and some clusters are selected for inclusion
Cross sectional study
researchers analyze data from a population, or a representative subset, at a specific point in time.
aka prevalence study
If doing cross sectional study for a large geographic region a
cluster sample will be conducted
Convenience population
non-probability based source population selected due to ease of access to those individuals.
Usually schools, workplaces, organizations, or communities.
Berkson’s Bias
Occurs when people are sampled from hospital and therefor are more likely to have comorbid conditions
Healthy worker bias
can occur when participants are recruited from occupational populations and thus are healthier than the general population
Exclusion bias
occurs when exclusion criteria are applied unevenly or if certain subgroups are excluded for reasons that affect the study’s findings.
Participation rate is the
Percentage of member of the sample population who are included in the study population
Selection bias
occurs when the members of the study population are not representative of the source population
nonresponse bias
If the members of a sample population who “agree” to participate are systemically different from those who refused to participate.
The strongest cross sectional surveys use
population-based studies that use probability based sampling
A Census is
a complete enumeration of a population
Case control study
a study that compares the exposure history of those with a disease and people without the disease.
Has inclusion and exclusion criteria
Hospitals, specialty clinics, public health offices, disease support groups and advocacy organization are _____ in case-control studies
Helpful
However we must make sure that the participants are not healthier or sicker or more or less socially connected
Nested case control study
is a type of observational study where a subset of cases (individuals with the outcome of interest) and controls (individuals without the outcome) are drawn from a “previously established” cohort that has been followed over time.
benefit: No recall bias because participants were followed and data was collected throughout the study not based on participant recall
cohort study
used to follow a group of people (a “cohort”) over time to determine how certain exposures or factors influence the development of outcomes, such as diseases or health conditions.
Experimental studies focus on
validity of the study and safety of participants
Qualitative data sampling
researchers have intense direct contact with a group of key informants
Key informant
individuals selected to participate in a qualitative study because they have expertise relevant to the study
Purposive sampling
Nonprobabiltiy-based sampling method that recruits participants for a qualitative study based on the special insights they can provide
The goal of qualitative studies is to reach
data saturation
Data saturation
a time in the research process in which no new information about a particular theory is emerging
Vulnerable populations
populations whose members might have limited ability to make an autonomous decision about volunteering to participate in a research study
Community involvement
Community buy in often facilitates access to source populations and improves participation rates
Resources are wasted when a study recruits
too many or too few participants
