SCMA Chapter 4: Measurement and Units of Analysis

A researcher investigates whether the number of hours students spend studying each week affects their final course grade. In this study, what is the dependent variable (DV)?

B) The final course grade

Students are asked to rate their satisfaction with a course on a scale of Very dissatisfied, Dissatisfied, Neutral, Satisfied, or Very satisfied. What is the level of measurement for this variable?

B) Ordinal

A researcher develops a scale to measure students' academic confidence. Students complete it twice and receive almost identical scores each time. However, most of the questions actually ask about how much students enjoy attending university. Which is the best assessment of this scale?

B) It is reliable, but its validity is questionable.

A variable's attributes must be exhaustive and mutually exclusive.

True

An extraneous variable is a variable that the researcher intentionally manipulates to see its effect on the dependent variable.

False

Match the level of measurement with its definition: Nominal

Attributes are exhaustive and mutually exclusive; no mathematical meaning.

Match the level of measurement with its definition: Ordinal

Attributes can be rank ordered, but the distance between them is not known.

Match the level of measurement with its definition: Interval

Attributes have equal distance between them, but no true zero point.

Match the level of measurement with its definition: Ratio

Attributes have a true zero point, allowing for ratios to be stated.

Reliability

The consistency of a measure; applying the same measure to the same person gives the same result each time.

Validity

The accuracy of a measure; it measures what it is intended to measure.

Stability

The type of reliability concerned with whether the same measure produces the same result over time.

Internal Reliability

The type of reliability concerned with whether items in a multi-item measure hang together as indicators of the same thing.

Inter-Observer Consistency

The type of reliability concerned with whether multiple observers reach the same judgments.

Internal Validity

Whether the study actually tests what it seeks to test.

External Validity

Whether the findings hold beyond the current study and can be generalized to other situations and contexts.

Variable

A grouping of several characteristics.

Attribute

The individual characteristics within a variable.

Exhaustive

Every person studied fits into one of the categories offered.

Mutually Exclusive

No person fits into more than one category.

Nominal Level

The most basic level of measurement; attributes are exhaustive and mutually exclusive with no mathematical meaning.

Ordinal Level

Attributes can be rank ordered, but the distance between them is not known.

Interval Level

Attributes have equal distance between them, but no true zero point.

Ratio Level

Attributes have a true zero point, allowing ratios to be stated.

Independent Variable (IV)

The variable that causes another; the variable the researcher manipulates.

Dependent Variable (DV)

The variable that is caused by another; the outcome being measured.

Extraneous Variable

A variable that may compete with the independent variable in explaining the outcome.

Confounding Variable

An extraneous variable that is the real reason for an outcome, confounding the relationship of interest.

Rival Plausible Explanation (RPE)

An alternative factor that may account for the results observed, other than what the researcher expected.

Standardized Procedures

Keeping all aspects of an experiment the same except the independent variable.

Random Assignation

Every participant has an equal chance of being assigned to any condition, independently of others.

Pre-Test Equivalence

The assumption that experimental and control groups are equal in all respects before the independent variable is administered.

Block Randomization

Every condition occurs once in random order before any condition is repeated.

Mortality

Participants leaving an experiment before it is over.

Maturation

Participants changing over time (e.g., getting older, developing).

History Threat

An event occurring after the treatment that may influence the dependent variable.

Testing Threat

The pre-test itself may influence the dependent variable.

Instrumentation Threat

Changes in the way a test is administered may account for pre-test and post-test differences.

Selection Threat

Post-test differences between groups may be caused by pre-existing differences.

Measurement Validity

Whether you are measuring what you want to measure.

Replicability

The results remain the same when others repeat all or part of a study.

Test-Retest Reliability

The same measure gives the same result when administered again later.

Cronbach's Alpha

A statistical measure of internal reliability for multi-item scales.