Assessment L6 - WAIS-IV (2)

Question 1

How do we interpret the WAIS-IV profile?

Answer 1

FSIQ: Based on 10 core subtests

Index Scores: Primary interpretation level

VCI & PRI: 3 core subtests each

WMI & PSI: 2 core subtests each

GAI = VCI + PRI

Optional Index score

Scoring criterion for the WAIS-IV presents upwards of 50 values. The approach to this wealth of information must therefore be systematic rather than by a random selection. This process can take place in NINE steps

Question 2

What kinds of scores do we get from the WAIS-IV profile?

Answer 2

• Standard scores
• Discrepancy analyses:
  Simple-Difference discrepancy analyses
  Predicted-difference discrepancy analyses

Question 3

What are standard scores?

Answer 3

• Norm scores
• INDIVIDUAL SCORES are compared to NORMATIVE GROUP, and the person’s ability in relation to others of the same AGE is established.

Question 4

What are discrepancy analyses?

Answer 4

• used to determine whether scores are different from one another
• assists in profile analysis
• provides means of interpreting score differences

Two different types:
Simple-difference
Predicted difference

Question 5

What is the simple-different discrepancy analysis

Answer 5

• Used in WISC-IV, WAIS-IV, WMS-IV.

- Subtract the scores from each other, then compare the obtained difference using CRITICAL VALUES and BASE RATES.

Question 6

What are base rates?

Answer 6

• the frequency with which a specific difference occurred in the normative sample
• used to determine if a statistically significant difference is rare and potentially clinically sig
• presented as %
• less frequent = more clinically relevant

Question 7

What are predicted different discrepancy analyses?

Answer 7

• represents the difference between PREDICTED and ACTUAL scores, which are compared with critical values and base rates.
• used to compare WAIS-IV and WMS-IV
• uses regression methodology to create predicted scores.

This is used to get a an idea of PRE-MORBID FUNCTIONING

Question 8

How do we assess premorbid functioning?

Answer 8

• National Adult Reading test - attempts to test premorbid intellectual functioning, as this is usually not affected by injury –> can alter this score according to education level, socio-economic status and age.
  Eg. How do you pronounce subtle?

Question 9

What is the FSIQ

Answer 9

Full scale IQ

• most reliable score on WAIS-IV
• mean split half reliability of .98 and stability coeff of .96
• standard error of 2 points
• overall measure of ability, represents the most sensible measure of overall functioning

NOT meaningful in neuropsych sense, rare that one would want a point estimate of IQ, but is important for ID determination

Question 10

What is the GAI

Answer 10

• General Ability Index
• provides summary score less sensitive than FSIQ to working memory and processing speed.
• It includes indices of VCI and PRI
• goal is to exclude PSI and WMI because these are thought to be the most sensitive to brain injury
• thus, is a more accurate measure than FSIQ in situations where there are big discrepancies between indices.

Question 11

When do you use the GAI

Answer 11

When there is great discrepancy (>1.5SD/23 POINTS) between the indices. suggests that the scores are not reliable.

Question 12

What is the CPI

Answer 12

This is the score that involves only the WMI and PSI.

It is a person’s proficiency for processing certain types of info..

These areas are thought to be very sensitive to brain damage.

Proposed that if we look at the discrepancy between CPI and GAI, we can see extent of injury

Question 13

When is it appropriate to calculate and interpret CPI and GAI

Answer 13

• need to check if they constitute unitary abilities
• GAI - is there a 1.5SD diff between VCI and PRI
• cpi - Is there a 1.5SD diff between PRI and WMI?

Question 14

What are the two paths for interpretation?

Answer 14

• Interpret the four indices of the WAIS-IV
  or
• Interpret the 5 factor model developed by Keith:
  1. Crystallised intelligence (Gc) = vocabulary + information
  2. Short-term memory (Gsm) = digit span + letter number
  sequencing (LNS)
  3. Visual processing (Gv) =block design and visual puzzles
  4. Fluid reasoning (Gf) = matrix reasoning + figure weights
  (FW)
  5. Processing speed (Gs) = symbol search + coding

can only use the keith model if the client is 16-69, and you have done the LNS and FW

Question 15

What is inter-subtest scatter?

Answer 15

• Check for significant scatter within the indices to determine whether each is measuring a unitary construct.

Do this by subtracting the lowest score from the highest score within the index, and it must be NO GREATER THAN 5 POINTS (1.5 SDs)

if it is greater than 5, then the index cannot be considered unitary and therefore should not be interpreted as a single construct.

Do this for each index

Question 16

Are index scores factors?

Answer 16

No, because theyre determined by not just factor analysis, but also THEORETICAL CONSIDERATIONS

Question 17

What does it mean if something is rare

Answer 17

If something is rare (has a base rate of 10% or less), it means that this occurs in 10% or less of the healthy controls

Question 18

What is a normative strength

Answer 18

When the standard score of an index is more than 115

1 SD above

Question 19

What is a normative weakness

Answer 19

When the standard score of an index is less than 85 (1 BELOW)

Question 20

How do we interpret strengths and weaknesses in subtest scaled scores

Answer 20

score - their own mean score = difference

check if significant, then compare to base rate.

The determination of whether the performance represents a personal strength or weakness is based on its uncommonness, using a 10% base rate criterion

This allows the examiner to identify key assets and high priority concerns in the individual’s cognitive profile

Question 21

What are some hypotheses that can be tested in the WAIS-IV

Answer 21

Current Status:

• Are the findings normal?
• is the compromise global or specific?
• which pathological process is at work? - difficult, as people can perform badly for MANY reasons, eg. believing that they have a brain injury.
• is there only one or more than one pathological processes at work?
• Is the patient’s presentation a genuine one, or is it due to some other cause, including the possibility of less than genuine effort?

Prior Status
- Do the findings represent a change from the prior level of functioning of this individual? - repeated measures analysis, using reliable change indices that take into consideration practice effects

Future Status:

• Do the findings represent a change from an assessment conducted earlier in the evolution of the condition?
• What are the implications of this deficit to the real world?

Question 22

What score difference between the indices would indicate that a summary score is not interpretable?

Answer 22

a difference that is larger than 1.5 SD (>23 points)

use when eg. checking if GAI or FSIQ is interpretable