Wechsler Intelligence Scale for Children | Fourth Edition

I administered the WISC–IV to a student who scored 65 on each of the VCI, PRI, WMI, and PSI indexes, but his FSIQ was 57. Shouldn't it be 65?

Many people find this result counterintuitive, but it is correct. First, consider that the FSIQ is used to predict the student's true intelligence and does not correlate perfectly with it.Then consider that the index scores are composed of fewer subtests than the full scale IQ score and do not correlate perfectly with the FSIQ. In this case, if the student's true IQ is 57, then his or her index scores should be higher than 57 due to the effect of regression toward the mean. On the other end of the continuum, the opposite is true. If a student's FSIQ is 147, there is a greater probability that his or her index scores will be lower than the FSIQ.

This effect can be found in the composite score norms tables of many tests of cognitive ability, though the strength of the effect depends on several factors, including the number of subtests entering the composite, and the distance of the subtest scores from the mean, and the correlation among those subtests.

When a composite is made up of more subtests, the effect is larger. It is rarer to score about 2 standard deviations below the mean on each of the 10 subtests that compose the FSIQ than on each of the two or three subtests that compose an index score.This is why the effect is more pronounced for the FSIQ than for any of the four Indexes.

The further a score is from the mean, the larger the effect. This is because it is rarer to score about 2 standard deviations from the mean on all 10 core subtests than it is to score 1 standard deviation from the mean all 10 subtests.The effect is usually more pronounced at 2 standard deviations from the mean than at 1 standard deviation from the mean. In WISC–IV, the effect is largest at approximately 2 standard deviations above or below the mean. Beyond this point, the minimum and maximum possible scores constrain the effect.

The regression toward the mean effect is stronger when there is a lower correlation among the subtests that make up the composite score.That is why the effect is stronger in WISC–IV than it was in WISC–III.Though the inter-correlations among the 10 core subtests that constitute the WISC–IV FSIQ are high, they are not as high as those for the WISC–III subtests.

These slightly lower correlations are related to the greater diversity of construct coverage among the core subtests in WISC–IV.This expanded construct coverage improves clinical utility, but weakens the inter-correlations among the core subtests, which in turn, increases the effect of regression toward the mean.

The mean scores for the MR groups reported in the WISC–IV Technical Manual are FSIQ = 60 (Mild MR group) and FSIQ = 46 (Moderate MR group), respectively.These two clinical studies provide evidence in support of the psychometric integrity of the normative data in this range of the distribution.

In a separate study of 84 children selected from the combined MR sample groups, the WISC–IV Index and FSIQ scores were compared with previously obtained WISC–III scores (mean re-test interval = 6 months). As shown in the following table, the results of the WISC–IV are consistent with the WISC–III scores.The mean FSIQ scores are almost identical.The corrected correlations between the composite scores of the two versions range from .83 to .90. In addition, 68% and 81% of the WISC–IV FSIQ scores are within the 95% and 99% confidence interval of the WISC–III FSIQ scores, respectively. Such results are similar to the test-retest results reported in the WISC–III and WISC–IV manuals, and supply an additional line of evidence in support of the validity of the test scores in this portion of the IQ range.

How is the FSIQ on WISC-IV different than the FSIQ on WISC-III?

Compared to the WISC–III, the WISC–IV FSIQ deemphasizes crystallized knowledge (Information is supplemental), and increases the contribution of fluid reasoning (Matrix Reasoning and Picture Concepts), working memory (Letter–Number Sequencing), and Processing Speed (both Coding and Symbol Search). The WISC–IV FSIQ is comprised of all 10 subtests that comprise the four index scores, including additional measures of working memory and processing speed.The WISC–III FSIQ included only one measure of processing speed and one measure of working memory in the FSIQ.

The new indices are made up either of two or three subtests. Are these as reliable as the former VIQ and PIQ?

Yes. Although the indices contain fewer subtests than in WISC–III VIQ and PIQ, the reliability is just as high for the indices as it was for the VIQ and PIQ.This is mostly due to the removal of subtests that demonstrated relatively lower reliability than those subtests that were retained and the highly reliable subtests that were added. 

Which GAI tables should we use? Four different GAI tables are provided in various sources, and they are not the same. Which one is endorsed by PsychCorp? The four sources are: WISC-IV Clinical Use and Interpretation (Prifitera, Saklofske & Weiss, 2005), Essentials of WISC-IV Assessment (Kaufman & Flanagan, 2004); WISC-IV & WPPSI-III Supplement Sattler & Dumont, 2004), and on the Dumont & Willis website.

The GAI tables provided by Prifitera, Saklofske & Weiss (2005) are the only GAI tables supported by The Psychological Corporation.That is because they were created using the actual WISC-IV standardization sample (n = 2,200), whereas the GAI tables provided in other sources were created using a statistical approximation (Tellegen & Briggs, 1967). Further, there are differences among the various tables based the Tellegen & Briggs formula depending on whether the scores were derived from sums of scaled scores on the subtests, or sums of standard scores on the Indexes, and all of those tables will differ from tables derived directly form the original normative data.The Tellegen & Briggs formula is appropriate for use in situations were the actual data are not available, and the tables provided by others were generated while practitioners were waiting for the actual tables to be created. Now that Prifitera et. al., have provided the actual tables, any GAI tables found in other sources should be considered approximations.The Tellegen & Briggs formula underestimates scores in the upper portion of the distribution and overestimates scores in the lower portion of the distribution. On average, this difference is about 2 to 3 points, but can be as much as 6 points in individual MR and gifted cases.Thus, practitioners are advised to use the GAI formulas found in WISC-IV Clinical Use & Interpretation (Prifitera, Saklofske, & Weiss, 2005). The book is published by Elsevier Science and now available at the www.elsevier.com, or by selecting Pearson Customer Service from the dropdown of our Contact Us page. 

Why are some 0 point or 1 point responses on the verbal subtests not queried?

In standardization it was determined that querying certain responses did not result in any additional information. If you feel the child has more knowledge, based on your clinical judgment, the child's performance on surrounding items, and other observations during the administration, you have the option to query. However, clearly wrong responses should not be queried. In addition, the responses marked with a Query in the manual, must be queried. 

Why is reliability lower for gifted children and children with mental retardation than children in the standardization sample?

It is a consistent finding that the restriction in the range of scores these groups obtain frequently results in lower reliabilities. 

Are there profiles typical of clinical disorders?

In general, the answer is no. However, ongoing research may identify certain characteristics of cognitive functioning for specific clinical disorders. While specific profiles are not diagnostic of particular disorders, working memory and processing speed are implicated in a variety of psychoeducational and neuropsychological disorders. 

The WISC–III has been adapted and standardized in 16 different countries. For children whose families have recently immigrated, these are the most current, valid tests available in their first language.Versions of these tests can be obtained by contacting PsychCorp and include adaptations for Canada, United Kingdom, France and French-speaking Belgium,The Netherlands and Flemish-speaking Belgium, Germany, Austria and Switzerland, Sweden, Lithuania, Slovenia, Greece, Japan, South Korea, and Taiwan. Use of these adaptations requires an examiner or experienced professional who is fluent in the child's language. 

In addition to these, the WISC–IV Spanish Edition is currently in development for use in the United States. Bilingual examiners (Spanish/English) and are urged to call PsychCorp at 1-800-228-0752, ext. 5218 if they interested in participating as examiners in the WISC–IV Spanish Edition standardization study. Standardization projects are underway for English language versions in Australia, England, and Canada that offer local normative information; a French Canadian version is also under development for use in French-speaking Canada. 

Why does WISC–IV start with Block Design?

Although Picture Completion has traditionally been the first subtest administered, it is not a core subtest in the WISC–IV. Block Design was chosen as the first subtest because it is an engaging task that allows the examiner additional opportunity to establish rapport.This is consistent with a recent revision of another Wechsler product, the WPPSI–III, where Block Design as the initial subtest has been well-received by examiners.When testing motorically challenged children, examiners may decide to begin with a different subtest in the interest of rapport.

If you wanted to reduce the effects of speeded performance, why not eliminate time bonus altogether from Block Design?

In general, higher ability children tend to perform the task faster.Without time bonuses, Block Design is not as good of a measure of high ability. 

The Picture Concepts subtest is scored with either 0 or 1 point.The keyed response represents the best single response in terms of the level of reasoning involved. 

For example, on more difficult items credit is not given for categories involving color or shape, emphasis is placed on underlying function.The keyed response was determined through years of research in Pilot,Tryout, and Standardization phases of development.The categories children provided, the ability level of children choosing specific responses, and relationships to performance on Similarities and Matrix Reasoning were all used to determine the keyed response. 

As noted in the third bullet under General Directions on page 126 of the Administration and Scoring Manual, certain responses to specific trials on Items 1, 4, and 5 require a prompt to remind the child of what the task is for this subtest.The prompt for Trial 1 of Item 1 is designed to remind the child to say the numbers first and then the letters. If the child forgets to say the number first (i.e., repeats exactly what you say), award credit for the trial as indicated and provide the prompt. Because the child received credit for his or her initial response to this trial, it is not necessary to award additional credit if the child attempts to correct his or her initial response after the prompt.

Trial 2 of Item 4 is the first trial in which the child is required to alphabetically sequence the letters to produce a correct response. If the child provides either of the specified incorrect responses by forgetting to alphabetically sequence the letters, provide the prompt as indicated. If the child provides a correct response to the trial after the prompt, do not award credit for the trial.

Similarly, Trial 1 of Item 5 is the first trial in which the child is required to sequence the numbers to produce a correct response. If the child forgets to sequence the numbers and provides either of the designated incorrect responses, provide the prompt as indicated. If the child provides a correct response to the trial after the prompt, do not award credit for the trial.

Children are more likely to guess correctly on the easier items such as those that appear in the first half of the item set, especially Item 9.The more difficult items found in the second half of the item set show a very low percentage of correct responses to the first clue. In order to respond correctly, even on the first clue, the child must use deductive reasoning; that is, on the first clue the child has to narrow the potential responses to those that fit a search set defined by the clue and then make a reasoned guess from the range of responses within the set. 

It is possible that a child who consistently guesses correctly on the first clue may have taken the test recently, or may have been coached on the correct responses. 

What will it take to upgrade to the integrated?

For an introductory period, the WISC-IV price plus the upgrade price will equal the price of the complete WISC-IV Integrated.

Will the WISC-IV Spanish be a "true" Spanish version or just a translation?

The WISC-IV Spanish will be a "true" Spanish version, developed from the "ground up" in Spanish. Some items, where appropriate, will be adopted from WISC-IV in English. However, the majority of the instrument will be developed in Spanish. A panel of scholars is working together to minimize the dialectic and regional differences from the variety of Hispanic nationalities that will be included in the standardization sample. Finally, the resulting scores will be equated to the WISC-IV norms so that Hispanic children can be measured and compared to the same scale.