Research Exam 2: Chapter 12 - Sampling

What types of questions are used to critique convenience sampling?

-What motivated participants to either participate or not participate? -What kind of data would have been obtained if nonparticipants had also responded? -How representative is the sample to the population? What kind of confidence can you have in the evidence provided by the findings?

What is simple random selection?

-a carefully controlled process -researcher defines the population (set) --> lists all the units of the population (sampling frame) --> and selects a sample of units (subset) from which the sample will be chosen

What are some examples of populations?

-all students attending nursing school in their final semester at CSULB -patients with stage III HF admitted to LBMMC in 2011 -all people with anxiety disorders in the US

What method is utilized to determine sample size in qualitative studies?

-data saturation -results in smaller sample sizes

What is inclusion criteria used for?

-determine the subjects used in a study by defining the criteria used to include or exclude a subject from the study

What are the disadvantages of stratified random sampling?

-difficult to obtain a population list containing complete critical variable information -time-consuming -enrolling proportional strata is challenging -large scale study is costly

What are the advantages of using convenience sampling?

-easy to recruit subjects

What are the advantages of stratified random sampling?

-enhanced representativeness of the sample (more so than quota sampling) -makes it possible to compare subsets -disproportionately small stratum can be oversampled to adjust for underrepresentation

When is probability sampling used?

-experimental -quasi-experimental

What is the goal of sample size in qualitative studies?

-fittingness is more important than representativeness

What is a population?

-humans, medical records, specimens -well-defined, set with specific parameters -can be broad or narrow

What are the disadvantages of cluster sampling?

-more sampling errors than with simple random or simple stratified -appropriate handling of statistical data from cluster samples is complex

What is nonprobability sampling?

-non-random selection -inclusion in a group is NOT random -less generalizable -less representative

What is stratified random sampling?

-population divided into homogenous strata or subgroups -allows for more representativeness -often confused with quota sampling

When is convenience sampling used?

-quantitative non-experimental -qualitative samples

What is probability sampling?

-random selection (each element of the population has an equal and independent change of being included in the sample) -uses randomization to assign elements -more generalizable -more representative

What are advantages of simple random selection?

-removes conscious biases -maximized representativeness -differences in the characteristics of the sample and the population are due to chance -increased sample size = decreased risk of choosing a non representative sample

What are the disadvantages of using convenience sampling?

-risk of bias greatest in this type of sample

What features should be used when describing the sample?

-sample size -demographic characteristics of the sample -inclusion and exclusion criteria -sampling strategy used -screening, recruitment, and enrollment protocol

How are sampling units (clusters) obtained in cluster sampling?

-simple random sampling -stratified random sampling

What is cluster sampling?

-successive random sampling of units (clusters) that progresses from large to small

What is the best sample size?

-the largest sample size possible using power analysis -add 15% to account for attrition -increases representativeness -"larger is better" is true for both non-probability and probability sampling -<10 = unstable/non-representative

What is sampling?

-the process of selecting subjects who are representative units of a designated population -the way by which we select a representative SAMPLE from the target POPULATION

What are disadvantages of simple random selection?

-time consuming -inefficient method of obtaining a random sample

What is the purpose of sampling/sample?

-to be more efficient -used when it is not cost-effective/feasible to study an entire population

What is selection effect?

-type of internal validity -bias because of subject self-selection OR -researcher bias in selecting

What is attrition and mortality?

-type of internal validity -loss of subjects from the study

What is exclusion criteria used for?

-used to control for extraneous variables or bias -minimize/control for sample bias

What are the 3 types of nonprobability sampling?

1. convenience 2. quota 3. purposive

What are the 4 steps in sampling strategies?

1. identify the target population 2. delineate the accessible population 3. develop a sampling plan 4. obtain approval from the IRB

What are the 2 types of sampling threats?

1. internal validity 2. external validity

What are the 2 types of sampling?

1. non-probability 2. probability sampling

What are the 2 types of internal validity?

1. selection effect 2. attrition and mortality

What are the 3 types of probability sampling?

1. simple random sampling 2. stratified random sampling 3. cluster sampling

A nurse conducted a research study that compared patient outcomes (length of hospital stay and perceived knowledge of disease process) in groups of 12-year-old patients with a diagnosis of epilepsy. Which are delimitations of this study? (Select all that apply.) Gender Age Socioeconomic status Diagnosis

Age Diagnosis Only 12-year-old patients were included. Only patients with a diagnosis of epilepsy were included. Attributes in subjects were not excluded or included such as gender or socioeconomic status.

A random sample of U.S. hospitals is surveyed to discover their nurse-to-patient ratios. What is the sampling frame for this study? All nurses hired by hospitals All U.S. hospitals All patients of the sample hospitals Hospitals responding to the survey

All U.S. hospitals All U.S. hospitals will have an equal opportunity to be included in the study. The units of the population from which subjects will be selected will not be nurses hired by all U.S. hospitals. The units of the population from which subjects will be selected will not be all patients of the sample hospitals. The definition of sampling frame is a list of all of the units of the population studied.

Which population meets criteria for being most available for study? A target population An accessible population A convenience sample A representative population

An accessible population An accessible population is available for participation in a study. The target population might or might not be accessible. Although a convenience sample is available, it cannot be considered a population of the study. Representativeness is an important characteristic of a sample, not of a population.

Methods of probability sampling include what? Cluster Convenience Quota Purposive

Cluster Cluster sampling is a method of probability sampling. Convenience sampling is a method of non-probability sampling. Quota sampling is a method of non-probability sampling. Purposive sampling is a method of non-probability sampling.

Which sampling method is considered to be either less or more time consuming depending on the strata? Purposive Quota Cluster Convenience

Cluster Cluster sampling is considered to be less or more time consuming depending on the strata.

To conduct a practice analysis of nurse aides, a researcher uses the outlined steps to select a sample of nurse aides: 1. Obtaining a random sample of all hospitals in the United States. 2. Acquiring a list of every aide working in those hospitals 3. Randomly selecting two aides from each hospital.What is this sampling technique used? Quota sampling Stratified random sampling Purposive sampling Cluster sampling

Cluster sampling The sample for this study was chosen by "clustering" each level of sample selection. In quota sampling, subjects are hand-selected to ensure a proportional number of subjects with selected characteristics. In stratified random sampling, the population is divided into strata, or subgroups, before random selection of subjects. A purposive sample is used when a highly unusual group is being studied.

In a nationwide study, a researcher collected blood samples from patients who had been diagnosed with clinical depression. The researcher also collected blood samples from each patient's nuclear family. Which sample technique did the researcher most likely use? Purposive Convenience Quota Random

Convenience Because the population of patients diagnosed with clinical depression is not known, quota sampling and random sampling were not possible. There were few selection criteria, making purposive sampling unnecessary. The easiest and most commonly used sampling technique is convenience sampling. Because the total population of patients with clinical depression is not known, handpicking a "typical" sample would be impossible. Because the total population of patients with clinical depression is not known, handpicking a representative sample would be impossible. Because the population of patients diagnosed with clinical depression is not known, random sampling was not possible.

Which sampling strategy is considered to be easy in terms of drawing a sample? Convenience Quota Simple random Stratified random

Convenience Convenience sampling is considered easy in terms of drawing a sample. Quota sampling is considered relatively easy in terms of drawing a sample. Simple random sampling is considered laborious in terms of drawing a sample. Stratified random sampling is considered time consuming in terms of drawing a sample.

Which sampling strategy is considered to be easy in terms of ease of drawing the sample? Purposive Quota Cluster Convenience

Convenience Convenience sampling is considered to be easy in terms of ease of drawing the sample.

Which sampling strategy is considered to have the greatest risk of bias of any strategy? Convenience Quota Simple random Stratified random

Convenience Convenience sampling is considered to have the greatest bias of any sampling strategy. Quota sampling does not have the greatest risk of bias of any of the sampling strategies. Simple random sampling does not have the greatest risk of bias of any of the sampling strategies. Stratified random sampling does not have the greatest risk of bias of any of the sampling strategies.

Which sampling strategy has a greater risk of bias as compared to other sampling strategies? Purposive Quota Cluster Convenience

Convenience Convenience sampling is known to have a greater risk of bias than any other sampling strategy.

What do methods of non-probability sampling include? (Select all that apply.) Cluster Convenience Quota Purposive Stratified random

Convenience Quota Purposive Convenience sampling is a method of non-probability sampling. Quota sampling is a method of non-probability sampling. Purposive sampling is a method of non-probability sampling. Cluster sampling is a method of probability sampling. Stratified random sampling is probability sampling.

Voluntary participation in a study may result in a sample that feels strongly about the issue being studied. This issue occurs in which type of sampling method? Convenience sampling Probability sampling Stratified random sampling Cluster sampling

Convenience sampling When a researcher selects a sample on the basis of convenience, the individuals willing to participate may do so because of their strong feelings about the topic being studied. They might not be representative of the larger population. With probability sampling, each member of the population has an equal chance of being included, thereby reducing the likelihood of having an overrepresentation of people with specific opinions. With any type of random sampling, each member of the population has an equal chance of being included, thereby reducing the likelihood of having an overrepresentation of people with specific opinions. With any type of random sampling, each member of the population has an equal chance of being included, thereby reducing the likelihood of having an overrepresentation of people with specific opinions.

Which statements are true about convenience sampling? (Select all that apply.) Convenience sampling is the most commonly used method of sampling. Convenience sampling is the strongest non-probability sampling strategy. Research consumers should be skeptical about the external validity of the finding. Convenience sampling provides level III evidence. A disadvantage is that it is difficult for the researcher to obtain subjects.

Convenience sampling is the most commonly used method of sampling. Research consumers should be skeptical about the external validity of the finding. The easiest and most commonly used method of sampling is convenience sampling. Convenience sampling is the weakest form of sampling strategy with regard to strength of evidence and generalizability and is at highest risk for problems with external validity. The risk of bias is higher than with any other type of sampling. Convenience sampling produces level VI evidence. An advantage of convenience sampling is that generally it is easier for the researcher to obtain subjects.

A quota sampling technique introduces what type of bias? Internal validity External validity Face validity Content validity

External validity As with any non-probability sample, the quota strategy contains an unknown source of bias that affects external validity. A non-probability sample does not necessarily introduce problems with internal validity. Face validity refers to the expert opinion of the validity of the content of the data-collection instrument and does not refer to sampling techniques. Content validity refers to the validity of the content of the data-collection instrument and does not refer to sampling techniques.

A research study explored the meaning of health for migrant farmworker women in a southern state. A convenience sample of 20 migrant farmworker women was surveyed. What is the population of this study? Migrant farmworker women in Georgia Migrant farmworkers Migrant farmworker women Migrant farmworkers in Georgia

Migrant farmworker women in Georgia The population of this study is migrant farmworker women in Georgia. The study looked only at migrant farmworker women, not at all migrant farmworkers. The study looked only at farmworkers in Georgia, not at those in any other state. The study looked only at migrant farmworker women, not at all migrant farmworkers in Georgia.

What is an example of inclusion and exclusion criteria?

Nursing students -Who are in their final semester in their BSN nursing program -Living in Southern California -Who are males between the age of 20-40 yrs -Who are not formally diagnosed with mental illness

What is true about both non-probability sampling techniques and probability sampling techniques? Non-probability sampling techniques are more rigorous. Each element has an equal chance of being included in the study with either technique. Probability sampling more likely results in a representative sample. Generalizability of findings is not possible with either technique.

Probability sampling more likely results in a representative sample. Probability, or random, sampling is more likely to provide a representative sample. Probability sampling is more rigorous. Only with probability sampling does each element have an equal chance of being included in the study. Generalizability is possible with probability sampling.

Which sampling strategy has bias that increases with the greater heterogeneity of the population? Purposive Quota Cluster Convenience

Purposive Purposive sampling is known to have bias that increases with the greater heterogeneity of the population.

Which sampling technique would the researcher most likely use to study specific characteristics of adult triplets who were raised separately? Convenience Quota Purposive Random

Purposive A purposive sample is used when a highly unusual group is being studied. Because relatively few subjects will meet the sample criteria, another sampling technique will be more appropriate. The quota technique is used when there are many characteristics that must be represented in the sample. Random selection would not be useful in this study because of the rarity of the target population.

Which sampling strategy has very limited ability to generalize because the sample is handpicked? Purposive Quota Cluster Convenience

Purposive Purposive sampling is known to have very limited ability to generalize because the sample is handpicked.

Which sampling strategy is considered relatively easy in terms of drawing a sample? (Select all that apply.) Purposive Quota Simple random Stratified random

Purposive Quota Purposive sampling is used to draw a highly unusual sample and therefore may not be relatively easy. Quota sampling is considered relatively easy in terms of drawing a sample. Simple random sampling is considered laborious in terms of drawing a sample. Stratified random sampling is considered time consuming in terms of drawing a sample.

What is the most important characteristic of a sample? Delimitation Purposiveness Representativeness Accessibility

Representativeness A sample must have characteristics that are similar to the larger population. The term delimitation refers to the exclusion and inclusion criteria for sample selection. The term purposive refers to a sampling approach, not to a sample characteristic. Although it is easier to have a sample that is readily accessible, there is another, more important characteristic.

What can jeopardize the representativeness of the sample regardless of the technique used? (Select all that apply.) A large sample size Equal representation of each sample subset Sample heterogeneity Subjects dropping out of the study Ability to replicate the study population

Sample heterogeneity Subjects dropping out of the study Ability to replicate the study population When the sample is heterogeneous, its representativeness is jeopardized. A high attrition rate can jeopardize the representativeness of the sample. A large sample size enhances the representativeness of the sample. An equal representation of each sample subset enhances the representativeness of the sample. Being able to replicate the study population enhances the study.

Which sampling strategy is considered laborious in terms of drawing a sample? (Select all that apply.) Convenience Quota Simple random Snowballing

Simple random Snowballing Simple random sampling is considered laborious in terms of drawing a sample. Stratified random sampling is considered time consuming and laborious in terms of drawing a sample. Convenience sampling is considered easy in terms of drawing a sample. Quota and snowballing sampling is considered relatively easy in terms of drawing a sample.

What sampling technique uses random numbers to select a sample from a list of possible subjects? Simple random sampling Stratified random sampling Non-probability sampling Cluster sampling

Simple random sampling One technique of randomly selecting a sample is to use random numbers and select from a list of all possible subjects. Stratified random sampling involves dividing the target population into strata or subgroups. Random sampling is not a type of non-probability sampling. Cluster sampling is a multistage process.

A researcher wanted to conduct a study of depression among men working in executive corporate positions. The researcher located 10 subjects by advertising and then invited each of those subjects to refer their acquaintances who met the study criteria. What is this sampling technique called? Snowballing Matching Clustering Systematic

Snowballing Snowballing refers to finding people who meet the study criteria through social networks. Matching refers to constructing an equivalent comparison sample group by filling it with subjects who are similar to each subject in the control group. Clustering refers to a multistage process of successive random sampling. There is no sampling technique called systematic.

Which sampling strategy is considered time consuming in terms of drawing a sample? Convenience Quota Simple random Stratified random

Stratified random Stratified random sampling is considered time consuming in terms of drawing a sample. Convenience sampling is considered easy in terms of drawing a sample. Quota sampling is considered relatively easy in terms of drawing a sample. Simple random sampling is considered laborious in terms of drawing a sample.

What should be considered when estimating a sample size? (Select all that apply.) The design of the study The time available for analyzing data The type of sampling procedure used The cost of collecting data Homogeneity of the attributes under investigation

The design of the study The type of sampling procedure used The cost of collecting data The design of the study helps determine the size of the sample that is necessary. The type of sampling procedure will influence the size of the sample. The cost of collecting data will influence the size of the sample. Because the sample size affects the strength of the evidence obtained, determination of the sample size should not depend on operational concerns. Heterogeneity of the attributes under investigation should be considered.

What is the purpose of establishing inclusion and exclusion criteria? To randomize sample selection To delineate an accessible population To control for potential bias To clarify the research question

To control for potential bias To control for extraneous variables and ensure a representative sample, inclusion and exclusion criteria are carefully established. Selection criteria do not affect randomization of subjects. Selection criteria do not necessarily ensure accessibility of the population. Selection criteria should be consistent with the research questions, but they do not clarify any part of the research question.

When is purposive sampling most useful? When few people are willing to participate When members of the target population are heterogeneous When a highly unusual group is being studied When many subjects drop out of a study before it is completed

When a highly unusual group is being studied When few people meet the selection criteria, researchers often form a sample from all those eligible people who are willing to participate. If few people are willing to participate, a convenience sampling technique is most useful. Random sampling techniques are best to use with heterogeneous populations. In quantitative research, sample selection occurs before data collection begins.

When is bias introduced into a study? When sample selection is carried out inconsistently When subjects do not volunteer to participate When probability sampling techniques are used When the population is homogeneous

When sample selection is carried out inconsistently Inconsistent sample selection jeopardizes the representativeness of the sample and introduces bias. Random sampling introduces the least amount of bias in the sample. Probability sampling introduces the least amount of bias in the sample. Homogeneity in the population reduces the likelihood of bias.

What is a sample?

a set of elements that make up a population

What are the disadvantages of purposive sampling?

assumes that errors of judgement in over representing or under representing characteristics of the population in the sample will tend to balance out

When should sample size be determined in quantitative studies?

before a study is conducted

When is a pilot study used?

before conducting a large study to determine the feasibility of conducting the larger study and establish that sufficient scientific evidence exists to justify more extensive research

What is an example of quota sampling?

city X has 5000 RNs 40% = BSN = 2000 20% = diploma = 1000 40% = ADN = 2000 pick 500 RNs for study (10%), recruited at convenience. The quota SHOULD be: 200 BSN 100 Diploma 200 ADN (since recruited at convenience - NOT randomized, therefore not probability sampling -- cannot be stratified random sampling)

What is an example of stratified random sampling?

city X has 5000 RNs stratum 1: 40% = BSN = 2000 stratum 2: 20% = diploma = 1000 stratum 3: 40% = ADN = 2000 pick 500 RNs for study (10%), RANDOMLY. 200 BSN 100 Diploma 200 ADN (subjects are randomly selected, 10% from each stratum)

What is another name for exclusion criteria?

delimitations

When should sample size be determined in qualitative studies?

during research

What is another name for inclusion criteria?

eligibility criteria

What is external validity?

generalizability - based on representativeness of the sample

What is the goal of quota sampling?

identify the strata of the population and proportionally represents the strata in the sample

Where is sample and sampling found?

in the methods section

What is quota sampling?

knowledge about characteristics of the population of interest used to build representativeness into the sample

What are the advantages of cluster sampling?

more economical in terms of time and money

What is another name for cluster sampling?

multistage sampling

What type of sampling is convenience sampling?

non-probability sampling

What type of sampling is network sampling?

non-probability sampling

What type of sampling is purposive sampling?

non-probability sampling

What type of sampling is quota sampling?

non-probability sampling

What is the strongest type of sampling strategy?

probability sampling

What type of sampling in simple random sampling?

probability sampling

What type of sampling is cluster sampling?

probability sampling

What type of sampling is stratified random sampling?

probability sampling

What types of research are purposive sampling usually used?

qualitative research

What should samples be?

representative

What is the most essential criterion in appraising a sample?

representativeness

What is an example of cluster sampling?

sample of critical care nurses 1. random sample of hospitals obtained from the American Hospital Association that meet eligibility criteria 2. list of critical care nurses practicing in each hospital inclusion criteria: a. CCRN with at least 3 years experience as critical care nurse b. at last 75% of CCRN's time spent in providing direct patient care in a critical care unit c. full-time employment at the hospital 3. random selection of 10 CCRNs from each hospital who meet this criteria

What is another name for network sampling?

snowballing

What is purposive sampling?

subjects are selected that are considered to be typical of the population

What is the target population?

the entire set of cases about which the researcher would like to make generalizations

What is an element?

the most basic unit about which information is collected in nursing- usually individuals/patients

What is the accessible population?

those who meet inclusion criteria and we can reasonably get

What is network sampling?

use of social networks to locate samples that are difficult or impossible to locate in other ways

What is convience sampling?

use of the most readily accessible persons or objects as subjects in a study ex: the first 100 people who entered the hospital this morning ex: volunteers

What are the advantages of purposive sampling?

useful in studying populations with unusual/rare characteristics

When might an entire population be used in a research study?

when the population size is very small

What does representative mean?

when the sample has the same key characteristics as the entire population

What must be included when discussing inclusion and exclusion criteria?

why the researcher chose these criteria