EBP module 3 & 5

sampling frame

A list of potential subjects obtained from various public or private sources.

probabilistic sampling

Methods for choosing subjects that use a random selection process to increase the chance of obtaining a sample that accurately represents the population from which it is drawn.

quantitative research paradigm

A research model that assumes an objective reality exists that is observable and can be measured through systematic, bias-free methods.

sampling error

Occurs when a sample has characteristics that are different from other samples and from the population from which the samples are drawn.

simple random sampling

A probabilistic sampling method in which each potential subject has an equal chance of being selected.

systematic sampling

A probabilistic sampling method in which the first subject is randomly selected from a group organized according to a known identifier (such as a birth date) and then all remaining subjects are chosen based on their numerical distance from the first individual.

stratified random sampling

A probabilistic sampling method in which subgroups of a population are identified and randomly selected to ensure their inclusion in a study.

cluster sampling

A probabilistic sampling method in which subjects are randomly selected from naturally occurring pockets of the population of interest that are geographically dispersed.

non-probabilistic sampling

Methods for choosing subjects that do not use a random selection process; as a result, the sample may not represent accurately the population from which it is drawn.

convenience sampling

A non-probabilistic sampling method in which investigators select subjects who are readily available (such as students).

snowball sampling

A non-probabilistic sampling method in which the initial subjects in a study recruit additional participants via word-of-mouth communication.

purposive sampling

A non-probabilistic sampling method in which investigators hand select specific individuals to participate based on characteristics important to the researchers.

blocked assignment

An assignment method in which the number of individuals in each group is predetermined; investigators randomly assign subjects to one group at a time until each quota is met.

matched assignment

An assignment method in which subjects are first divided into subgroups based on a specific characteristic such as age, gender, and so forth; members of each subgroup are then randomly assigned to each group in the study to balance the characteristics across the groups.

power

The probability that a statistical test will detect, if it is present, a relationship between two or more variables (or scores) or a difference between two or more groups (or scores).

type II error

A result from a statistical test that indicates no significant relationship or difference is present when in fact one exists (i.e., a false negative). usually due to low sample size

measurement error

The difference between the true value (if it were observable) and the obtained value

measurement reliability

The extent to which repeated measurements agree with one another.

internal consistency

The degree to which subsections of an instrument measure the same concept or construct.

concepts

A mental image of an observable phenomenon that is expressed in words.

constructs

A non-observable abstraction created for a specific research purpose; defined by observable measures such as events or behaviors.

parallel forms reliability

Reliability of a self-report instrument established by testing two versions of the tool that measure the same concepts or constructs.

split-half reliability

Reliability of a self-report instrument established by testing two versions of the tool that are combined into one survey administered at one time; investigators separate the items and compare results for the two forms after subjects complete the instrument

intrarater reliability

The stability of repeated measures obtained by the same examiner.

interrater reliability

The stability of repeated measures obtained by two or more examiners. need to establish this for measures if you are having >1 person measure through a study

measurement validity

The degree to which a measure captures what it is intended to measure.

face validity

A subjective assessment of the degree to which an instrument appears to measure what it is designed to measure.

content validity

The degree to which items in an instrument represent all of the facets of the variable being measured.

construct validity

The degree to which a measure matches the operational definition of the concept or construct it is said to represent.

convergent validity

A method of construct validation that reflects the degree to which two or more measures of the same phenomenon or characteristic will produce similar scores.

discriminant validity

A method of construct validation that reflects the degree to which an instrument can distinguish between or among different phenomena or characteristics.

criterion validity

The degree to which a measure of interest (i.e., the "index measure") relates to a measure with established validity (i.e., the "criterion measure"/gold standard)

concurrent validity

The degree to which a measure of interest (i.e., the "index measure") relates to a measure with established validity (i.e., the "criterion measure").

predictive validity

A method of criterion validation that reflects the degree to which the score on a measure predicts a future criterion score.

independent variable

Traditionally defined as the variable that is purposefully manipulated by investigators in an effort to produce a change in outcome.

dependent variable

The outcome of interest in a study.

extraneous variable

Individual, organizational, or environmental characteristics other than the factor of interest (i.e., test, predictor, intervention) that may influence the outcome of a study.

discrete variable

A variable for which the value is a distinct category.

standard error of measurement

The extent to which observed scores are disbursed around the true score if it were observable.

measurement error

The difference between the true value (if it were observable) and the obtained value.

minimal detectable change

The amount of change that just exceeds the standard error of measurement of an instrument.

floor effect

A limitation of a measure in which the instrument does not register a further decrease in score for the lowest scoring individuals.

ceiling effect

A limitation of a measure in which the instrument does not register a further increase in score for the highest scoring individuals.

minimal clinically important difference

The smallest change in response to an intervention that would result in a change in patient or client management.

internal validity

In experimental and quasi-experimental research designs, the degree to which a change in the outcome can be attributed to the experimental intervention rather than to extraneous factors.

research validity

the extent to which a quantitative study of any type produces truthful results

external validity

The degree to which quantitative research results may be applied to other individuals and circumstances outside a study.

threats to internal validity related to subjects

selection, assignment, attrition, maturation, compensation, diffusion

why might selection be a threat

- access to the population of interest is limited and/or

- the method used to choose participants results in a sample that is not representative of the population of interest.

assignment

- inadequate assignment procedures may threaten research validity (internal validity) by producing groups that are different from one another at the start of the study.

nonexperimental studies

A study in which controlled manipulation of the subjects is lacking; in addition, if groups are present, assignment is predetermined based on naturally occurring subject characteristics or activities. when randomization insnt possible

attrition

A term that refers to subjects who stop participation in a study for any reason; loss of subjects may threaten research validity (internal validity) by reducing the sample size and/or producing unequal groups.

bias

Results or inferences that systematically deviate from the truth or research methods that produce such a deviation.

maturation

A threat to research validity (internal validity) characterized by the natural processes of change that occur over time in humans that may influence a study's results independent of any other factors.

compensatory rivalry

A threat to research validity (internal validity) characterized by subjects in the control (comparison) group who, in response to knowledge about group assignment, change their behavior in an effort to achieve the same benefit as subjects in the experimental group.

resentful demoralization

A threat to research validity (internal validity) characterized by subjects in the control (comparison) group who, in response to knowledge about group assignment, limit their efforts in the study.

solutions to compensation

masking, placebo

diffusion of treatment

A threat to research validity (internal validity) characterized by a change in subject behavior that may occur as a result of communication among members of different study groups.

statistical regression to the mean

A threat to research validity (internal validity) that may occur when subjects produce an extreme value on a single test administration; mathematically the next test scores for these individuals mostly will move toward the mean value for the measure.

threats to internal validity related to investigator

compensatory equalization of treatment

compensatory equalization of treatment

A threat to research validity (internal validity) characterized by the purposeful or inadvertent provision of additional encouragement or practice to subjects in the control (comparison) group in recognition that they are not receiving the experimental intervention.

threats to internal validity related to study logistics

history, instrumentation, testing,

history

A threat to research validity (internal validity) characterized by events that occur during a study that are unrelated to the project but may influence its results.

instrumentation

A threat to research validity (internal validity) characterized by problems with the tools used to collect data that may influence the study's outcomes.

measurement reliability

The extent to which repeated measurements agree with one another.

measurement validity

The degree to which a measure captures what it is intended to measure.

testing

A threat to research validity (internal validity) characterized by a subject's change in performance due to growing familiarity with the testing or measurement procedure or to inconsistent implementation of the procedures by study personnel.

construct validity

The degree to which a measure matches the operational definition of the concept or construct it is said to represent.

construct underrepresentation

A threat to construct validity characterized by measures that do not fully define the variable or construct of interest.