Chapter 9: Examining Populations And Samples In Research Flashcards
Is a particular group of individuals or elements to be studied
Population
the individual units of population(defines the selected group of people or elements)
Sample
an entire set of individuals or elements who meet the sampling criteria
Example: adult males, 18 years of age or older, diagnosed with type 2 diabetes, and hospitalized with a lower extremity infection
Target population
the portion of the target population to which the researcher has reasonable access (might include individuals within a state, city, hospital, or nursing units)
Example: Patients with diabetes who are in an acute care hospital in Dallas, TX
Accessible populations
election of subset of a population to represent the whole population
(Defines the selection process)
Sampling
characteristics that the subject or element must possess to be part of the target population
Example: adults 60 years of age or older, ability to speak and read English, and undergoing surgical replacement of one knee joint
Inclusion criteria
characteristics that can cause a person or element to be excluded from the target population
Example: any study participant with a history of previous joint knee replacement surgery, diagnosis of dementia, and diagnosed with a debilitating chronic muscle disease were excluded from the preoperative teaching study
Exclusion criteria
Means that the sample, accessible population, and target population are alike in as many ways as possible
-in terms of characteristics such as age, gender, ethnicity, income, and education, which often influence study variables
Representativeness
extending the findings from the sample under study to the larger population. Extent is influenced by quality of study and consistency of the study’s findings.
Example: the findings from the study of male patients, diagnosed with type 2 diabetes, and hospitalized with an infection in Dallas, may be generalized to the target population of males with type 2 diabetes hospitalized in Texas urban hospitals or, more broadly, to urban hospitals in the southern United States. With this information, you can decide whether it is appropriate to use this evidence in caring for the same type of patients in your practice, with the goal of moving toward evidence-based practice
Generalization
number of participants ,events, behaviors, or situations, examined in a study.
Sample size
blueprint for conducting a study; maximizes control over factors that could interfere with the validity of findings and guides the planning and implementation of a study in a way that is most likely to achieve the intended goal
Research design
random = equal chance (each person or element in a population has an opportunity to be selected for a sample
• Probability Sampling (Generalizability ↑)
what are the types of probability sampling?
- simple random
- cluster random
- stratified random
- systemic random
most basic of the probability sampling plans and is achieved by randomly selecting elements from the sampling frame (computerized).
Simple Random
used in situations in which the researcher knows some of the variables in the population that are critical for achieving representativeness
Example, using race and ethnicity for __________, the researcher may define four strata: white non-Hispanic, black non-Hispanic, Hispanic, and other. The population may be 60% white non-Hispanic, 20% black non-Hispanic, 15% Hispanic, and 5% other. Researchers may select a random sample for each stratum equivalent to the target population proportions of that stratum.
Stratified; stratification
a researcher develops a sampling frame that includes a list of all the states, cities, institutions, or clinicians with which elements of the identified population can be linked
Example: the researcher may first randomly select states and then randomly select cities within the sampled states. Next, the researcher may randomly select hospitals within the randomly selected cities. At this level, all patients on the nursing unit who fit the criteria for the study may be included or patients can be randomly selected
Cluster sampling
is used when an ordered list of all members of the population is available. The process involves selecting every kth individual on the list, using a starting point selected randomly.
Example: if the population size is N = 1200 and the desired sample size is n = 100, then k = 12. Thus, the researcher would include every 12th person on the list in the sample
Systemic random
Non-randor, not every element of a population has an opportunity to be selected for a study sample
Non-probability Sampling (Generalizability ↓)
Types of non-probability sampling
- convenience
- purposeful
- theoretical
- network
- quota
also called accidental sampling, is a relatively weak approach because it provides little opportunity to control for biases; participants are included in the study merely because they happen to be in the right place at the right time
ex: A classroom of students, patients attending a specific clinic, individuals in a support group, and patients hospitalized with a particular medical diagnosis are examples of ——— samples.
Convenience sampling
uses a convenience sampling technique with an added feature—a strategy to ensure the inclusion of participant types likely to be underrepresented in the convenience sample, such as females, minority groups, older adults, and the poor, rich, and undereducated.
Quota sampling
Judgmental or selective sampling, the researcher consciously selects certain participants, elements, events, or incidents, to include in the study
Example, researchers describing grief following the loss of a child might include parents who lost a child in the previous 6, 12, and 24 months, and the children who were lost might be of varying ages (< 5, 5 − 10, and > 10 years old). Ultimate goal of _______ sampling is selecting information-rich cases from which researchers can obtain in-depth information for their studies.
Purposeful sampling
Or snowball sampling, chain, or nominated sampling, hold promise for locating participants who would be difficult or impossible to obtain in other ways or who had not been previously identified
Ex: if a study were being conducted to describe the lives of adolescents who are abusing substances, ——- sampling would enable researchers to find participants who have a prolonged history of substance abuse and who could provide rich information about their lives in an interview.
Network sampling
is used in qualitative research to develop a selected theory or model through the research process.researcher gathers data from any person or group who can provide relevant, varied, and rich information for theory generation.
The data are considered relevant and rich if they include information that generates, delimits, and saturates the theoretical codes in the study needed for theory generation
Theoretical sampling
In quantitative studies what are factors that influence the adequacy of sample size:
Effect Size types of quantitative studies number of variables measurement sensitivity data analysis techniques
**uses power analysis
In Qualitative studies what are important factors that need to be considered in determining sample size:
Scope of the study
nature of the topic
quality of the data
study design
*uses data saturation
the size of difference between the groups or the strength of the relationship between two variables.
Effect size
Small effect size
<0.30 or < -0.30
Medium effect size
= 0.30 to 0.50 or -0.30 to - 0.50
Large effect size
> 0.50 or >-.50
What are the types of settings?
Natural setting
partially controlled
highly controlled
uncontrolled, real-life situation environment
researcher does not manipulate or change the environment for the study
Natural or field setting
is an environment that is manipulated or modified in some way by the researcher
Ex, private conference room in clinic, but in non business hours to reduce noise
Partially controlled setting
is an environment structured for the purpose of conducting research
Ex. Laboratories research or experimental centers, and test units in hospitals or facilities
Highly controlled setting
__________is an effective way to determine an adequate sample size for quantitative and outcomes studies.
In __________, effect size, level of significance (a = 0.05), and standard port(0.8 or 80%) are used to determine sample size for a prospective study and evaluate the sample size of a complete study
Power analysis; power analysis
Individual units of the population and sample
*participants
Elements
