Psychology in the Schools Volume 24, April 1987

STABILITY OF THE KAUFMAN ASSESSMENT BATTERY FOR CHILDREN FOR A SAMPLE OF AT-RISK PRESCHOOL CHILDRENIr2

MARK A. LYON AND DOUGLAS K. SMITH3

University of Wisconsin-River Falls

This study examined the stability of the Kaufman Assessment Battery for Children (K-ABC) for a sample of at-risk preschool children. Over a 9-month time interval, the stability coefficients (corrected for restriction in range) for the global scales of the K-ABC ranged from .78 to .88. The stability coefficients (corrected for restric- tion in range) for the K-ABC subtests ranged from .65 to .79. It was concluded that scores on the K-ABC for at-risk preschool children display adequate stability, but that the Simultaneous scale appears to be more amenable to change than either the Sequential or Achievement scales.

With the enactment of PL 94-142, a federal mandate was issued requiring the pro- vision of educational and related services to handicapped children aged 3-21. Since that time, an increasing concern of educators has been the identification of preschool children who are at risk for a variety of handicapping conditions (Lichtenstein & Ireton, 1984). Additionally, the focus of preschool assessment has changed to include not only diag- nosis, but also the design of appropriate intervention strategies (Kelley & Surbeck, 1983).

Several measures of cognitive ability have been developed during the past 15 years that purport to aid in the identification of preschool children who are at risk for learn- ing problems. These include the McCarthy Scales of Children’s Abilities (MSCA) (McCarthy, 1972), Kaufman Assessment Battery for Children (K-ABC) (Kaufman & Kaufman, 1983), and the Stanford-Binet Intelligence Scale: Fourth Edition (Thorndike, Hagan, & Sattler, 1986). In order to establish validity for these instruments, numerous studies comparing the performance of preschoolers on the scales have been reported (i.e., Gingrich, Detwiler, & Bush, 1986; Krohn, 1986; Lyon & Smith, 1986; Zucker, 1985).

However, the stability of performance among preschool children on these scales has received little attention. Of several recent investigations that have examined stabil- ity of performance, few have used preschool samples (i.e., Telzrow, Proefrock, & Hartlage, 1985; Valencia, 1985). Telzrow et al.’s study included 26 preschool children who had been identified as high-risk infants and were tested at ages 3, 4, 5, and 6 with either the Stanford-Binet (Form L-M) or the Wechsler Preschool and Primary Scale of Intelligence (WPPSI). The correlations with age 6 Stanford-Binet IQ ranged from .48 with Stanford-Binet IQ at age 5 to .56 with WPPSI Full Scale IQ at age 4. A limita- tion of this study, however, was that the stability coefficients were not corrected for restriction in range, making generalization of the results difficult.

Valencia’s (1985) study included 42 Mexican-American children enrolled in a Head Start program. Each student was evaluated with the K-ABC in spring, 1983 and

Requests for reprints should be addressed to Mark A. Lyon, Dept. of Psychology, University of Wisconsin- River Falls, River Falls, WI 54022.

‘Supported in part by Grant No. 1040-4-84 from the University of Wisconsin-River Falls Institutional Research Committee.

’A former version of this paper was presented at the annual convention of the National Association of School Psychologists, Hollywood, FL, April 1986.

3The authors wish to thank Ms. Karen Wilson and Ms. Vici Jernigan for their cooperation in the com- pletion of this research. We also wish to thank the many school psychology students who assisted with data collection and data entry for the project.

111

112 Mark A. Lyon and Douglas K. Smith

reevaluated in fall, 1983. Over this time interval (4-6 months), global scale stability co- efficients (corrected for restriction in range) ranged from .76 to .90. Individual subtest stability coefficients (corrected for restriction in range) ranged from .26 to .89. Valencia also reported a sizeable practice effect on the Simultaneous Processing Scale (gain score = 6.0). He noted that this is not a desirable property of an intelligence test, par- ticularly in view of the fact that the Achievement score, which might be expected to increase, showed no gain (gain score= - .07).

As new scales for preschool assessment are developed, it is important that the stabil- ity of performance on the instruments be examined. It is especially important that such data are collected for at-risk children, since placement decisions are partially based on performance on these measures. The purpose of this study was to investigate K-ABC stability for a sample of at-risk preschool children enrolled in two early intervention programs.

METHOD Subjects

The subjects for this study consisted of 53 preschool children ranging in age from 49 months to 73 months ( M = 53.11; SD= 3.63). The sample included 38 males and 15 females. All of the children had been identified as at risk for learning problems on the basis of scoring in the lower 10% of children on the Developmental Indicators for the Assessment of Learning-Revised (DIAL-R). They were later evaluated with either the MSCA or Stanford-Binet (Form L-M) and placed in one of two early intervention pro- grams, depending upon the district in which they resided. Both districts are located in suburban, midwestern communities and serve predominantly white children from lower- middle to upper-middle SES families. Procedure

The K-ABC was administered to each child in fall, 1984 and readministered in May, 1985, providing a 9-month interval between assessments. The evaluations were com- pleted by the two authors, who were certified school psychologists, and four school psychology interns, who had received training in K-ABC administration and interpreta- tion. All protocols were checked for scoring accuracy before being included in data analysis. Data Analysis

In order to examine the stability of K-ABC global scale and subtest scores, Pear- son product-moment correlations were performed between Time l and Time 2 scores. Because the majority of standard deviations for the K-ABC scores were smaller than those reported for the standardization sample, the obtained stability coefficients were corrected for restriction in range via Guilford’s (1954) formula. This procedure allows for a more appropriate comparison of stability coefficients between this sample of students and those found for the standardization group; however, because the coefficients have been corrected, they should be interpreted with caution. To examine mean differences in global scale and subtest scores, t-tests (two-tailed) for related samples were computed between Time 1 and Time 2 scores.

RESULTS AND DISCUSSION The descriptive results of the study, t values, and stability coefficients for the global

scales of the K-ABC are presented in Table 1. As can be seen, all four global scales

K-ABC Stability 113

increased significantly over the 9-month period of intervention. The Simultaneous (SlM) scale increased most (about .7 So>, changing from a mean of 87.93 at Time 1 to 97.21 at Time 2. This gain of 9.3 standard score points on the SIM scale is somewhat greater than the gain reported by Kaufman and Kaufman (1983) for a group of preschoolers (n = 84) in the standardization sample (gain = 7.2) and than the gain reported by Valen- cia (1985) (gain = 6.0). This may be due to the increased length of the time interval be- tween assessments in the present study. Additionally, it is doubtful (with a 9-month in- terval between assessments and 2 completely different SlM subtests administered at Time 2) that this gain can be attributed to practice effects. It is interesting to note, for exam- ple, that the mean scaled scores for Magic Window (8.17) and Face Recognition (7.70) at Time 1 are near the same levels as Gestalt Closure (8.11) and Triangles (8.51) at the time of first assessment. Similarly, the mean scaled scores for Spatial Memory (9.28) and Matrix Analogies (10.14) at Time 2 are near the same levels as Gestalt Closure (10.13) and Triangles (9.66) at the time of second testing. Because of the long interval between assessments, it is not possible to draw conclusions about the reasons for this general improvement in SlM performance (i.e., different subtests, intervention, practice); however, it seems unlikely that the change is due entirely to the effects of practice.

Table 1 Means, Standard Deviations, t Values, and Stability Coeflcients on the K-ABC Global Scales at Time 1 and Time 2

Variable M SD ta r rb

MPC Time 1 Time 2

Sequential Time 1 Time 2

Simultaneous Time 1 Time 2

Achievement Time 1 Time 2

85.81 93.04

86.83 89.21

87.93 97.21

89.11 92.59

11.98 12.14 7.53** .83 .88

10.38 10.86 2.20* .73 .84

13.92 13.82 7.01** .76 .78

12.70 12.18 3.37** .82 .87

aDegrees of freedom = 52. bCorrected for restriction in range.

**p< .001. * p < . 0 5 .

The Mental Processing Composite (MPC) increased by about .5 SD (from 85.81 to 93.04) during intervention. This appears to be largely a function of the marked im- provement in SIM performance, as the Sequential (SEQ) mean increased by only .15 SD (from 86.83 to 89.21). The improvement in Achievement (ACH) performance was similar to that of SEQ performance, changing from 89.1 1 at Time 1 to 92.59 at Time 2 (about .25 SO).

The descriptive results of the study, t values, and stability coefficients for the K-ABC subtests are presented in Table 2. Significant increases were obtained on both SIM subtests that were administered at Time 1 and Time 2, on all 3 ACH subtests, but on only 1 of 3 SEQ subtests. The change in performance on both Hand Movements and Number

114 Mark A . Lyon and Douglas K. Smith

Recall was negligible, whereas the change in Word Order (from 8.10 to 8.57) was sig- nificant. This change, however, represents an increase of only about .15 SD. Clearly, the significant increase in overall SEQ performance was facilitated most by this improve- ment in Word Order, while both Hand Movements and Number Recall remained rela- tively unchanged over the 9-month interval.

Table 2 Means, Standard Deviations, t Values, and Stability Coeficients on the K-ABC Subtests at Time 1 and Time 2

Variable" M SD tb r r'

Hand Movements Time 1 Time 2

Time 1 Time 2

Time 1 Time 2

Triangles Time 1 Time 2

Word Order Time 1 Time 2

Time 1 Time 2

Arithmetic Time 1 Time 2

Time 1 Time 2

Gestalt Closure

Number Recall

Faces & Places

Riddles

7.68 8.19

8.11 10.13

7.98 8.09

8.51 9.66

8.10 8.57

88.30 92.66

85.76 89.47

93.64 97.22

2.15 2.25

3.63 3.35

2.71 2.97

1.77 2.53

1.77 1.88

14.18 14.70

12.40 12.87

13.99 11.88

1.74

6.30***

.34

4.14***

2.34*

3.10**

2.76**

2.43"

.53

.78

.64

.61

.56

.75

.70

.67

.65

-

.68

.79

.74

.77

.77

.70 ~ ~ ~~~

=Magic Window, Face Recognition, Matrix Analogies, Spatial Memory, Expressive Vocabulary, and Reading Decoding were not included in these analyses due to insufficient n at either Time 1 or Time 2 testing.

bDegrees of freedom = 52. 'Corrected for restriction in range.

*p< .05. **p< .01.

***p<.001.

The stability coefficients for the global scales of the K-ABC (see Table 1) are highly consistent with those reported by Kaufman and Kaufman (1983) for preschool children in the Interpretive Manual and by Valencia (1985) for a sample of Mexican-American preschoolers. The coefficients (corrected for restriction in range) ranged from .78 on the SIM scale to .88 on the MPC. The stability coefficients (corrected for restriction in range) for the K-ABC subtests are also similar to those reported earlier, ranging from .65 on Hand Movements to .79 on Triangles. As might be expected, these coefficients are not as high as those for the global scales, but are generally adequate using a stand- ard of r> .70. The very low stability coefficients reported by Valencia for Riddles (r = .26)

K-ABC Stability 115

and for Hand Movements ( r= .39) were not obtained in this study ( r= .70 and -65, respectively).

The patterns of subtest strengths and weaknesses and global scale processing preferences also were examined at the time of initial and second testing. Whereas the number of individual subtest strengths and weaknesses did not change between testings, the processing preferences changed markedly. At the time of original testing, only 30% of the children displayed a processing preference (p< .05) on the K-ABC (13% SEQ and 17% SIM). At the time of retesting, however, 50% of the children displayed a pro- cessing preference (9Vo SEQ and 41 070 SIM). A chi-square analysis performed on these data documented a trend toward more children displaying a SIM preference at Time 2 compared to Time 1, x2(1)=3.01; p = .07.

The results of this study lend further support to the stability of the K-ABC with preschool children, and more specifically with at-risk preschoolers. With regard to the relative standing of individual children, the global scales appear to assess preschoolers’ abilities and skills in a stable manner over time, even when a relatively long interval is used between assessments. It is acknowledged, however, that the SIM scale of the K-ABC appears to be more amenable to change than either the SEQ or ACH scales. In previous studies where a shorter time interval between assessments was used, the effects of practice may be primarily implicated in sizeable SIM gains. In this study, however, it is not possible to draw such conclusions, due to the possible effects of intervention, different SIM subtests at Time 2 assessment, and other factors. The question of what accounts for larger gains in SIM performance over longer intervals of time for preschool children appears to merit further investigation.

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