Ch 9: Examining Populations and Samples in Research

Match the definitions with the types of sampling. Specific selection of subjects with certain characteristics by the investigator to be in the study: a. Convenience sampling b. Probability sampling c. Cluster sampling d. Quota sampling e. Network sampling f. Purposive sampling

Purposive sampling Correct With purposeful sampling, sometimes referred to as "judgmental" or "selective sampling," the researcher consciously selects certain participants, elements, events, or incidents to include in the study.

Match the definitions with the types of sampling. Technique used to select underrepresented groups in the population: a. Convenience sampling b. Probability sampling c. Cluster sampling d. Quota sampling e. Purposive sampling f. Network sampling

Quota sampling Correct Quota sampling uses a convenience sampling technique with an added feature—a strategy to ensure the inclusion of subject types likely to be underrepresented in the convenience sample, such as females; minority groups; and the older, poor, rich, and undereducated. The goal of quota sampling is to replicate the proportions of subgroups present in the target population.

Match the definitions with the types of sampling. Expected difference in values that occurs when examining different subjects from the same sample: a. Random variation b. Systemic variation c. Target population d. Sampling frame

Random variation Correct Random variation is the expected difference in values that occurs when different subjects from the same sample are examined. The difference is random because some values will be higher and others lower than the average (mean) population value. As sample size increases, random variation decreases, improving representativeness.

Match the definitions with the types of sampling. Phenomenon that occurs when the selected subjects—measurement values vary in some way from those of the population: a. Random variation b. Systemic variation c. Target Population d. Sampling frame

Systemic variation Correct Systematic variation, or systematic bias—a serious concern in sampling—is a consequence of selecting subjects whose measurement values differ in some specific way from those of the population. This difference usually is expressed as a difference in the average (or mean) values between the sample and the population.

Match the definitions with the types of sampling. The number of subjects who meet the criteria of the study: a. Random variation b. Systemic variation c. Target population d. Sampling frame

Target population Correct The target population is the entire set of individuals or elements who meet the sampling criteria (defined in the next section), such as female, 18 years of age or older, new diagnosis of type 2 diabetes confirmed by the medical record, and not on insulin.

Match the definitions with the types of sampling. Subjects are not selected with probability sampling methods: a. Convenience sampling b. Probability sampling c. Cluster sampling d. Quota sampling e. Purposive sampling f. Network sampling

a. Convenience sampling Correct Convenience sampling, also called "accidental sampling," is a weak approach because it provides little opportunity to control for biases; subjects are included in the study merely because they happen to be in the right place at the right time.

Which of the following would the nurse would not consider when critiquing the adequacy of a sample? a. Possibility of a type I error b. Potential biases in the sample c. Sample size d. Sampling criteria

a. Possibility of a type I error Correct Type I error is not useful in judging the adequacy of a sample. The risk of a type II error, formally examined using power analysis, is prevented with an adequate sample size.

Which of the following is a type of nonprobability sampling? a. Purposive b. Simple random c. Stratified d. Systematic

a. Purposive Correct Purposive or judgmental sampling is a nonprobability sampling method that involves the conscious selection by the researcher of certain subjects or elements to include in a study. Simple random sampling, stratified sampling, and systematic sampling are probability sampling methods.

How can the adequacy of a quantitative study's sample size best be evaluated? a. Analyzing the samples of previous studies b. Conducting a power analysis c. Determining the number of subjects in the target population d. Examining the design validity

b. Conducting a power analysis Correct A power analysis is the best way to determine the adequacy of the sample size to protect against making a type II error in quantitative studies. Power is the capacity of the study to detect differences or relationships that exist in the population.

The sample includes adults over the age of 18, able to read and speak English, and hospitalized for their first abdominal surgery. What is this an example of? a. Exclusion sampling criteria b. Inclusion sampling criteria c. Population statistics d. Sample characteristics

b. Inclusion sampling criteria Correct Adults over the age of 18, able to read and speak English, and hospitalized for their first abdominal surgery are examples of inclusion sampling criteria. Inclusion criteria are those characteristics that the subject or element must possess to be part of the target population. Exclusion criteria identify participants that are ineligible to join the study. Population and sample characteristics are descriptive features of the population

Nurse researchers wanted to study the characteristics of parents who have abused their children. They initially identified parents who consented to participate in the study. Next, they asked these subjects to identify other individuals who might participate in the study. What sampling method was used in this study? a. Convenience b. Network c. Purposive d. Systematic

b. Network Correct Network or snowball sampling takes advantage of social networks and the fact that friends tend to have characteristics in common to identify subjects who would be difficult, if not impossible, to obtain in any other way. Convenience sampling, also called accidental sampling, is a relatively weak approach because it provides little opportunity to control for biases; subjects are included in the study merely because they happen to be in the right place at the right time. Purposive or judgmental sampling is a nonprobability sampling method that involves the conscious selection by the researcher of certain subjects or elements to include in a study. Systematic 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.

Match the definition with the types of sampling. Sample selection ensures that each element has a chance to be selected for the study. a. Convenience sampling b. Probability sampling c. Cluster sampling d. Quota sampling e. Purposive sampling f. Network sampling

b. Probability sampling Correct In probability sampling, every member (element) of the population has a probability higher than zero of being selected for the sample. To achieve this probability, the sample is obtained randomly.

Match the definitions with the types of sampling. List of every potential subject in the population: a. Random variation b. Systemic variation c. Target population d. Sampling frame

d. Sampling frame For everyone in the accessible population to have an opportunity for selection in the sample, each person in the population must be identified. To accomplish this, the researcher must acquire a list of every member of the population, using the sampling criteria to define eligibility. This list is referred to as the sampling frame. Researchers then select subjects from the sampling frame using a sampling plan.

Which of the following methods provides a sample that is most likely to be representative of the target population? a. Convenience sampling b. Purposive sampling c. Quota sampling d. Simple random sampling

d. Simple random sampling Correct Simple random sampling is a probability sampling method designed to achieve representativeness of the sample. Convenience, purposive, and quota sampling methods are nonprobability methods that produce a sample that has a higher potential for bias and is less representative of the population than a sample selected with a probability sampling method

A researcher was conducting a phenomenological study of the lived experience of losing a limb. A convenience sampling method was used to obtain subjects. Subjects were recruited for the study until an equal number of males and females were obtained. The total sample was 14 (7 males and 7 females). What is the sampling method used in this study? a. Purposive b. Quota c. Stratified random d. Systematic

b. Quota Correct The sampling method described in this example is quota sampling. Quota sampling is a convenience sampling technique with an added strategy to ensure the inclusion of subjects who are likely to be underrepresented in the convenience sample, such as women, minority groups, and undereducated people. Purposive or judgmental sampling is a nonprobability sampling method that involves the conscious selection by the researcher of certain subjects or elements to include in a study. Stratified random sampling is used in situations in which the researcher knows some of the variables in the population that are critical for achieving representativeness. Systematic 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.

The number of participants or sample size in a qualitative study is adequate when which of the following occurs? a. A power analysis indicates the power of 0.8 is achieved. b. Saturation of data is achieved, and additional subjects provide no new information c. The sample size is large enough to identify differences between groups in the study. d. The statistical analysis techniques identify significant findings.

b. Saturation of data is achieved, and additional subjects provide no new information. Correct In qualitative studies, the sample size is adequate when saturation of data is achieved in the study area. Saturation of data occurs when additional sampling provides no new information, only redundancy of previously collected data. Power analysis, finding significant differences between groups, and using statistical analyses to identify significant findings are important in judging the adequacy of sample size in quantitative studies.

A researcher asked nurses in a hospital to participate in a study that examined the leadership of the hospital. A total of 500 subjects were asked to participate, and 200 consented to be in the study. What is the refusal rate for this study? a. 20% b. 40% c. 60% d. 80%

c. 60% Correct Five hundred subjects were asked to participate and 300 refused. The refusal rate is 300 ÷ 500 = 60%. The acceptance rate was 200 ÷ 500 = 40%.

Match the definition with the types of sampling. Obtaining a population where composing a sampling frame is severely inhibited: a. Convenience sampling b. Probability sampling c. Cluster sampling d. Quota sampling e. Purposive sampling f. Network sampling

c. Cluster sampling Correct In cluster sampling, a researcher develops a sampling frame that includes a list of all the states, cities, institutions, or organizations with which elements of the identified population can be linked. A randomized sample of these states, cities, institutions, or organizations can then be used in the study. In some cases, this randomized selection continues through several stages and is then referred to as multistage sampling.

The sample for a study was randomly selected from a list of registered nurses (RNs) obtained from the Board of Nurse Examiners (BNE) for Texas. The study had a cultural focus, so the final sample included 100 Caucasian, 100 Hispanic, and 100 African American RNs. What type of sampling method was used in this study? a. Convenience b. Simple random c. Stratified random d. Systematic

c. Stratified random Correct This study used a stratified random sampling method. This sampling method is used in situations in which the researcher knows some of the variables in the population, such as ethnicity, age, gender, or medical diagnosis, which are critical for achieving representativeness. In this study, the subjects were stratified by ethnic background to increase the sample's representativeness of the population. Convenience sampling, also called accidental sampling, is a relatively weak approach because it provides little opportunity to control for biases; subjects are included in the study merely because they happen to be in the right place at the right time. Simple random sampling is the most basic of the probability sampling plans. It is achieved by randomly selecting elements from the sampling frame. Systematic 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.

A nurse researcher conducted a grounded theory study of the self-care behavior of patients diagnosed with type 2 diabetes. Ten subjects were selected because they were judged to have strong self-care behavior, and 10 subjects were selected because of their poor self-care behavior. What sampling method was used in this study? a. Cluster b. Convenience c. Network d. Purposive

d. Purposive Correct Purposive sampling was used in this study because the researcher consciously selected subjects because they were judged to have strong or poor self-care behavior. In cluster sampling, 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. Also known as multistage sampling, groups, not individuals, are randomly selected. Convenience sampling, also called accidental sampling, is a relatively weak approach because it provides little opportunity to control for biases; subjects are included in the study merely because they happen to be in the right place at the right time. Network sampling (also known as snowball sampling) involves sampling of participants based on referrals from others already in the sampl

A research article states that "participants were recommended by others already in the study." What is this an example of? a. Convenience sampling b. Quota sampling c. Random sampling d. Snowball sampling

d. Snowball sampling Correct In snowball sampling, the researcher asks the participants to recommend others in circumstances similar to theirs. Convenience sampling, also called accidental sampling, is a relatively weak approach because it provides little opportunity to control for biases; subjects are included in the study merely because they happen to be in the right place at the right time. Quota sampling uses a convenience sampling technique with an added feature—a strategy to ensure the inclusion of subject types likely to be underrepresented in the convenience sample. Random sampling is the selection of a sample such that each member of a population has an equal probability of being included.

A researcher asked nurses in a hospital to participate in a study that examined the leadership of the hospital. A total of 500 subjects were asked to participate, and 200 consented to be in the study. What does the sample in this study demonstrate? a. A probability sampling method b. Quota sampling c. Representativeness d. Systematic variation

d. Systematic variation Correct Systematic variation or bias is great when a large number of the potential subjects decline to participate in a study, resulting in a high refusal rate. In this study, 300 subjects refused to participate for a 60% refusal rate.

A researcher selected only people with a high intelligence quotient (IQ) to be in her study so that they would perform well on the multiple-choice tests administered to measure the subjects' knowledge in the study. This study demonstrates which of the following? a. Cluster sample b. Representative sample c. Stratified random sample d. Systematic variation in the sample

d. Systematic variation in the sample Correct Systematic variation or bias is a consequence of selecting subjects whose measurement values differ in some specific way from those of the population. In this example, the subjects selected had a mean IQ higher than the members of the population. In cluster sampling, 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. Representative sample is a sample whose characteristics are comparable to those of the population from which it is drawn. Stratified random sampling is used in situations in which the researcher knows some of the variables in the population that are critical for achieving representativeness.

According to sampling theory, findings can be generalized to the a. individuals in the same social class as the sample. b. individuals receiving care in the same type of setting. c. sample under study. d. target population.

d. target population. Correct One should be able to generalize findings to the target population.

Match the definitions with the types of sampling. Securing individuals through social contacts for the study: a. Convenience sampling b. Probability sampling c. Cluster sampling d. Quota sampling e. Purposive sampling f. Network sampling

f. Network sampling Correct Network sampling, sometimes referred to as "snowball, chain, or nominated sampling," holds promise for locating participants who would be difficult or impossible to obtain in other ways or who have not been previously identified for study (Patton, 2002; Munhall, 2007). Network sampling takes advantage of social networks and the fact that friends tend to have characteristics in common. This strategy also is particularly useful for finding subjects in socially devalued populations.