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Defining assessment

What is the purpose of assessing?

Assessments can be used to serve several distinct purposes, including:

  • diagnosis,
  • prognosis,
  • research,
  • planning intervention, or
  • measuring outcomes (Coelho et al., 2005).


There are a variety of terms used when discussing types of assessments. The following definitions aim to provide some clarity around relevant terminology.

Standardised assessments are assessments in which the procedure for administering the test items are prescribed and well defined (Coelho et al., 2005).  These assessments often allow comparisons against normative samples. All other assessments are nonstandardized.

Norm Referenced tests yield results that can be quantitatively compared with performance of a normative sample (e.g., age corrected scores and standard scores based on a normal comparison group). A criterion referenced test is one that yields results that are compared with a standard other than performance of a normative sample. The Western Aphasia Battery is an example of a criterion-referenced test. The goal is to determine aphasia severity rather than to place individuals with aphasia on a continuum with a normal comparison group (Coelho et al., 2005).

Formal and informal are used in various ways. Coelho et al (2005) describes a formal assessment tool as one that has systematically applied procedures, whereas an informal assessment is described as lacking defined procedures. In this sense, the broad category of formal measures includes both standardized measures with specifically prescribed administration procedures and other systematic assessments such as functional behaviour assessment.

An alternative perspective is that  formal assessment processes are those used  for the purposes of replication, for example, when the purpose of the assessment is to compare the person with aphasia to  a normative reference standard or to compare their performance over time.  Informal assessment processes are those used for the purposes of developing an in-depth understanding of an individual’s performance and difficulties in relation to their identified needs and the scope of the assessment (e.g. to design therapy, to consider decision-making capacity). For these reasons, Ferguson (2008) has suggested the adoption of the term ‘individualised’ when describing this latter approach to assessment.

Additionally, some people refer to informal assessments as those taken from research articles or developed by clinicians but not published commercially. These often lack any psychometric properties.

Dynamic Assessments are considered to undertake an experimental approach in the sense that they attempt to identify the effects of factors (e.g., strategies, task modifications, context factors, environmental supports) that may influence performance (Coelho et al., 2005).




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Professor Linda Worrall
The University of Queensland
ST LUCIA QLD 4072   



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