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Assessment Instrument Glossary
In the clinical context, the primary goal of assessment
is to determine those characteristics of the client and
his or her life situation that may influence treatment decisions
and contribute to the success of treatment. Additionally,
assessment procedures are crucial to the treatment planning
process, which involves the integration of assessment information
concerning the person's substance use behavior, substance-related
problems, and other areas of psychological and social functioning.
Assessment instruments may also be geared towards assessing
the treatment and treatment process itself, or in assessment
of treatment outcomes.
Norms allow the test performance of a given client to be
compared with that of a large, relevant group of individuals.
No instrument is validly useful for all people. While norms
are essential to describe a single case of a sample by comparison
to a larger group, they are less important, for example,
in contrasting pretreatment and post-treatment behavior
in an individual. In determining the importance of normative
information, the clinician should be concerned about whether
norms are available that would assist in making clinical
decisions in a particular case. Phrased differently, would
the demographic characteristics of a client affect the interpretation
of the score and influence choice of treatment?
Reliability: A measure is considered reliable if
it would give the same result over and over again. Reliability
is measured several ways:
- Inter-rater (or joint): A measure of agreement
between two or more observers evaluating the same subjects
and using the same information. Used to assess the degree
to which different raters give consistent estimates of
the same phenomenon.
- Test-retest (or stability): A measure of agreement
between evaluations at two points in time. One would expect
high stability on measures that tap stable client characteristics,
such as family history of alcoholism, age of onset of
problem drinking, and general expectancies of alcohol
effects. Scales for more transient client characteristics,
such as craving and treatment motivation, would be expected
to have lower test-retest reliability.
- Internal (or internal consistency): Reflects
agreement of content coverage within the scale itself.
Internal consistency assess how well responses on individual
items correlate with those of other items of the scale.
Internal consistency is often assessed by correlating
performance on two halves of a test ("split-test").
For instruments designed to measure a single phenomenon,
such as severity of the alcohol dependence syndrome, these
correlational coefficients should be high.
Validity: Refers to the degree to which a test measures
what it is intended to measure. A test is valid for a particular
purpose or for a particular group. Validity is measured
in three ways:
- Construct: Refers to the degree to which a measure
actually taps a meaningful hypothetical construct and
a nondirectly observable, underlying causal or explanatory
dimension of behavior. Scales measuring hypothetical constructs
such as "craving," "loss of control,"
and "denial," should yield high levels of construct
- Content: Refers to the degree to which the content
of a measurement is related to the phenomenon or trait
that it purports to measure. For example, a checklist
of alcohol consequences should comprise the multiplicity
of adverse effects of drinking, rather than singling out
certain negative consequences to the minimization or exclusion
of others that are equally damaging. Content validity
is not quantified. Rather, it must be built into the test
by careful construction and selection of test items, and
is based on the content of a single measurement instrument.
- Criterion: Refers to how well scores on a measure
relate to important, relevant nontest (real world) behaviors,
such as initial motivation for treatment and long-term
maintenance of sobriety. Criterion validity is a major
concern in evaluating screening tests and is gauged by
the extent to which individuals who score positive on
them actually receive a diagnosis of alcoholism and vice
versa. Predictive, concurrent, and "postdictive"
validity are all types of criterion validity. The distinctions
among them reflect the temporal relationship between the
test results and the phenomenon of interest.
- Discriminate (convergent or divergent):
The extent to which an instrument is effective in distinguishing
between two or more groups of individuals with respect
to specific traits or characteristics. For example, a
test of drug abuse that has discriminate validity would
make it possible to classify some individuals as definite
drug abusers, others as mild drug users (who use drugs
only occasionally) and still others who are almost totally
free of drug use.
- Face: The items of the test deal with information,
questions, or problems related to the stated objectives
of the test.
Screening refers to the formal process of testing to identify
individuals with substance-related problems or consequences,
or those who are at risk for such difficulties. Screening
is used to determine whether a client does or does not warrant
further assessment at the current time. It typically involves
answering a "yes" or "no" question:
Does the client being screened show signs of a possible
mental health, substance-related, or co-occurring disorder?
Note that the screening process does not necessarily identify
what diagnosis the person may have, or how serious it might
be, just whether or not further assessment is warranted.
Negative Predictive Value: The propotion of people
who screen negative that actually do not have the disease.
Positive Predictive Value: The
proportion of people who screen positive that actually have
Sensitivity: The proportion
of diseased people who are correctly identified as "positive"
by the measure.
Specificity: The proportion
of non-diseased people who are correctly identified as "negative"
by the measure.
SOURCES: Assessing Alcohol Problems: A Guide for Clinicians
and Researchers, 2nd ed. Edited by: John P. Allen, Veronica
B. Wilson. (NIH Publication No. 03-3745). Bethesda, MD: National
Institute on Alcohol Abuse and Alcoholism, 2003. Available
on-line at: http://pubs.niaaa.nih.gov/publications/Assesing%20Alcohol/index.htm. Assessing Drug Abuse among Adolescents and
Adults: Standardized Instruments: NIDA Clinical Report Series.
Alfred S. Friedman and Samuel Granick. (NIH Publication No.
94-3757), Rockville: National Institute on Drug Abuse, 1994.