ch 12

A nurse researcher should be concerned about establishing clear eligibility criteria for inclusion in a study sample because such criteria: increase the homogeneity of the sample. decrease the homogeneity of the sample. increase the size of the sample. decrease the size of the sample.

ANS: A Clear eligibility criteria are designed to increase the homogeneity of the sample. Clear eligibility would not hinder homogeneity but support it. Eligibility criteria do not directly increase or decrease sample size. Eligibility criteria do not directly increase or decrease sample size.

A nurse researcher would hesitate to use nonprobability sampling because: a. it will result in reduced or limited generalizability. b. informed consent must be obtained. c. it will require large, unmanageable sample sizes. d. sample sizes are too small for most methods of statistical analysis.

ANS: A Non-probability sampling reduces or limits generalizability. Informed consent is used for all studies despite choice of sample used. Non-probability sampling does not mandate large unmanageable sample sizes. Non-probability sampling does not mandate a small sample size.

A nurse researcher can most accurately use the technique of power analysis: to estimate sample size. to establish sampling strata. to assign subjects randomly. to analyze sample representativeness.

ANS: A Power analysis is a statistical procedure used to estimate needed sample size. Sampling strata would be determined by knowledge of population strata. A table of random numbers (or a computer program) can be used to assign subjects randomly. Sample representativeness is not determined by power analysis.

What is the process of selecting representative units of a population for study in a research investigation? Sampling Snowballing Delimination Random assignment

ANS: A Sampling is the process of selecting representative units of a population for a research study. Snowballing is a sampling technique using social networks. Delimination is the specification of sample characteristics. Random assignment is the process of assigning subjects to groups.

A nurse researcher should be particularly concerned about having a small sample size because: a. there is increased risk of obtaining a non-representative sample. b. there is increased risk of a study subject interacting with another study subject. c. there is increased potential for loss of confidentiality. d. there is increased regression toward the mean.

ANS: A Small sample sizes tend to increase the risk of a sample being non-representative. Study subject interaction can occur, whatever the sample size. Confidentiality loss can affect large or small samples. Regression toward the mean is not generated by sample size.

A nurse researcher opts to use a stratified sample in a research study because: a. the sample population is divided into subsets that are homogeneous for a particular trait or feature. b. the sample population is divided into subsets for random assignment into an intervention or a usual-care group. c. the sample population is randomly assigned to a specific subgroup that will vary from the others on the basis of type of treatment. d. the sample population is randomly assigned to a specific subgroup that will vary from the others on the basis of treatment duration.

ANS: A The major characteristic of a stratified sample is that selected subjects represent population subgroups that are homogeneous. A stratified sample would have representation in both the treatment and control groups. In a stratified sample, both treatment and control groups have representative groups. Stratified samples are not devised on the basis of length of treatment but on proportions of subjects in the population.

A nurse researcher should attempt to clearly specify exclusion criteria for a study sample because such criteria will: a. limit the time needed to complete the study. b. reduce the effect of extraneous variables on the accurate evaluation of the outcome variable. c. eliminate the outside influences and inferences regarding the effectiveness of a behavioral intervention. d. ensure that an adequate sample size is accrued to meet assumptions for accurate statistical analysis.

ANS: B Exclusion criteria do not directly affect how long a study takes. Exclusion criteria are designed to control sample characteristics and thereby reduce the potential effect of extraneous variables on the outcome variable. Exclusion criteria delimit the sample but do not fully act as controls for the intervention. Sample size is not determined by exclusion criteria.

Which statement is most accurate regarding inclusion and exclusion criteria? a. These criteria are not needed when the population being studied is composed of events. b. These criteria serve to ensure that the characteristics of the sample and the population are congruent. c. Inclusion criteria are used to define the independent variables, and exclusion criteria are used to define dependent variables. d. Inclusion criteria are used to define the dependent variables, and exclusion criteria are used to define independent variables.

ANS: B Inclusion and exclusion criteria are always needed in some form. Inclusion and exclusion criteria are designed to keep the population and sample characteristics congruent. Inclusion and exclusion criteria refer to sample subjects rather than to independent or dependent variables. Inclusion and exclusion criteria refer to sample subjects rather than independent or dependent variables.

The researcher used word of mouth to accrue a sample of participants. This is known as: a. referral. b. networking. c. recruitment. d. quasi-probability.

ANS: B Referral is a generic term and is not associated specifically with word-of-mouth technique. Networking is a sampling strategy using word-of-mouth via social networks. Recruitment is the term used to describe the methods used to obtain research subjects. Quasi-probability is a term that is unassociated with word-of-mouth sample approaches.

The primary characteristic of a probability sample is considered to be: self-selection of subjects. random selection of the sample. subjects handpicked by the researcher. representation of proportional segments of the population.

ANS: B Self-selection of subjects would be antithetical to probability sampling. The primary characteristic of a probability sample is random selection. Subjects being handpicked by a researcher represent a purposive sample, which is not a form of probability sampling. Proportional segment representation can be found in quota sampling, which is a form of non-probability sampling.

A study's sampling strategy is most likely to be discussed in which section of the research report? Conclusion Results Literature review Abstract

ANS: B The conclusion of the research report does not usually contain information about the sampling strategy that was utilized since it will tend to include a summary of information about the study. A discussion of the study's sampling strategy may be briefly mentioned in the methods section of a research report. A more lengthy discussion including statistical information will most likely be included in the results section of the report. The literature review will discuss a synopsis of various studies that were found to be pertaining to the study but do not include information regarding the sampling strategy. The abstract is a brief summary of the study overall and will not contain information regarding the sampling strategy utilized

A researcher consumer should evaluate sample size in a research report: a. by asking how many assistants were involved in data collection. b. by asking how representative the sample is relative to the target population. c. by asking how great the outcome difference is between or among study groups. d. by asking how many previous studies the researcher has conducted on similar topics.

ANS: B The number of data collectors is not of critical importance for research report evaluation. A major factor to be evaluated about sample size is how representative of the population the sample is. Outcome differences would have greater impact on later research but not on the current study. Researcher expertise should not determine sample size.

A nurse researcher has made a generalization on the basis of the experience of a small number of participants. The result of this will most likely show: a. the small sample will invalidate the hypotheses. b. the researcher will be unable to eliminate his or her bias. c. the data obtained from a small number will inadequately represent the phenomenon. d. the small number of participants will increase the threat to internal validity influenced by history.

ANS: C A small sample does not necessarily invalidate hypotheses. Researcher bias is not necessarily controlled by sample size, small or large. A too-small sample may inadequately represent the phenomenon and threaten valid conclusions. Small sample size does not necessarily increase historical threats to validity.

What can a nurse researcher use to restrict the study population to homogeneous groups of subjects? Sampling Self-selection Eligibility criteria Defining study limitations

ANS: C Sampling does not mandate restricting the population to a homogeneous group of subjects. Self-selection would not restrict subjects to a homogeneous group. Eligibility criteria restrict or control the homogeneity of subjects in relation to the population. Specifying study limitations would not restrict subjects to homogeneity.

The nurse researcher knows that a sample is representative of a population when: the sample is homogeneous. all units of a population are included. the most readily accessible persons are used as subjects. the characteristics of the sample closely approximate those of the population.

ANS: D A homogeneous sample is not the ultimate criterion for evaluating a sample. Population elements or unit inclusion is important but not the ultimate criterion. Ready subject accessibility does not constitute the most important evaluative criteria. The foremost criterion in evaluating a sample is its representativeness.

How should a nurse researcher expect a sample to differ from a population? a. A sample can mean objects or events, whereas population refers to individuals or groups of people. b. A population has a broad set of defining characteristics, and a sample has a narrow set of defining characteristics. c. A population is a representative segment of a defined sample. d. A sample is a representative segment of a defined population.

ANS: D A population refers to a well-defined set of people, animals, objects, or events. A sample is the group of research subjects representing the population. A sample is a representative segment of the population. A sample is a set of elements or segments of a specified population.

How can a nurse researcher tell the difference between an accessible population and a target population? a. The accessible population meets the inclusion criteria, and the target population meets the exclusion criteria. b. The target population meets the inclusion criteria, and the accessible population meets the exclusion criteria. c. The accessible population represents the entire set of cases the researcher wishes to study, and the target population represents that part of the accessible population that could feasibly be included in the study. d. The target population represents the entire set of cases the researcher wishes to study, and the accessible population represents that part of the target population that could feasibly be included in the study.

ANS: D Inclusion and exclusion criteria refer to subject characteristics, not components of the population. Inclusion and exclusion criteria refer to desirable and undesirable subject characteristics. The target population is the entire set of cases to be studied; the accessible population is the part of the population that can be studied. The target population is the entire set of cases the researcher wants to study; the accessible population meets population criteria and is available for study.

Which type of sampling is most at risk for sample bias? a. Quota b. Random c. Purposive d. Convenience

ANS: D Quota sampling, if done appropriately, will not create sample bias. Random sampling should act to counteract sample bias. Purposive sampling would selectively include research subjects and avoid sampling bias. Convenience sampling is most at risk for sample bias.

The nurse researcher can most accurately determine sample size by considering what? The stamina of the researcher in data collection The importance of the independent variable The age of the potential subjects The design of the study

ANS: D Researcher stamina should have no impact on sample size selection. Importance of the independent variable does not mean anything unless it is measured as effect size. Subjects' age should not affect the size of a sample. A major factor determining sample size is the type of design used.

Which statement regarding sample size is most accurate? Studies with smaller sample sizes have more accurate results. Studies with smaller sample sizes are more likely to be representative of the target population. Studies with larger sample sizes have more accurate results. Studies with larger sample sizes are more likely to be representative of the target population.

ANS: D Smaller sample sizes may be associated with less accurate results. Smaller sample sizes are more likely to be unrepresentative of the population. Sample size does not guarantee accuracy of the results. In general, studies with larger sample sizes are more representative of the population.