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USE OF THE TELLEGEN AND Briggs formula TO DETERMINE the Canadian Dumont-Willis-Beal Indexes (CAN-DWBI-1 & CAN-DWBI-2) for the Canadian WISC-IV[1]
 
Ron Dumont, John O Willis and A. Lynne Beal
 
In this short paper, we provide two alternative composite scores (CAN-DWBI-1 and CAN-DWBI-2) for the WISC-IV with Canadian norms. CAN-DWBI-1 is derived from the three subtests that enter the VCI and the three subtests that enter the PRI. CAN-DWBI-2 is derived from the two subtests that enter the WMI and the two subtests that enter the PSI. We refer to these composites as the Canadian Dumont-Willis-Beal Indexes (CAN-DWBIs) in order to distinguish them from the traditional ten-subtest Full Scale IQ. The Canadian Dumont-Willis-Beal Indexes separates the six subtests that are stronger measures of verbal and non-verbal intelligence from the other four subtests that are not as highly correlated with FSIQ (i.e., Digit Span, Letter-Number Sequencing, Coding, and Symbol Search).
 
The CAN-DWBI-1 score is a six-subtest composite that excludes subtests which load on the WMI and PSI.
 
The CAN-DWBI-2 score is a four-subtest composite that includes subtests which load on the WMI and PSI.
 
Examiners may wish to report CAN-DWBIs when the Verbal (VCI) and Perceptual (PRI) abilities are found to be close to one another yet significantly different from those of the Working Memory (WMI) or Processing Speed (PSI) abilities.
 
The tables for the CAN-DWBIs are provided below. These tables were developed using the procedures described for the American Dumont Willis Index 1 (DWI-1) and the Dumont-Willis Index-2 (DWI-2).  The procedure uses the WISC-IV Canadian subtest intercorrelations (Table 5.1, page 67, WISC-IV Canadian Manual[2]) and the Tellegen and Briggs procedure[3].   Conceptually, the Canadian Dumont-Willis-Beal Index-1 parallels the General Ability Index (GAI) developed by Prifitera, Weiss, and Saklofske[4] for the sum of scaled scores for the eight VCI and POI subtests of the WISC-III.  Prifitera, Weiss, and Saklofske's table was based directly on the WISC-III Canadian normative data. 
 
Similarly, the Canadian Dumont-Willis-Beal Index-2 is based on the sum of scaled scores for the Digit Span and Letter-Number Sequencing (WMI) and Coding and Symbol Search (PSI) subtests.  This score is very similar to Alan Kaufman's "third factor"[5] and "SCAD"[6] scores.  It should be computed and considered only when the four WMI and PSI subtest scores are close to one another and substantially separate from the VCI and PRI subtests.  In those cases, the CAN-DWBI-1 and CAN-DWBI-2 scores may be an efficient alternative means of summarizing the 10 WISC-IV core subtests, but they must never be confused with Canadian normative WISC-IV factor and IQ scores.
 
To use these tables, first calculate the Canadian Dumont-Willis-Beal Index-1 Sum of Scaled Scores (CAN-DWBI-1 SSS) by adding the scaled scores for the following six subtests: Similarities, Vocabulary, Comprehension, Block Design, Picture Concepts, and Matrix Reasoning.
 
Second, calculate the Canadian Dumont-Willis-Beal Index-2 Sum of Scaled Scores (CAN-DWBI-2 SSS) by adding the scaled scores for the following four subtests: Digit Span, Letter-Number Sequencing, Coding, and Symbol Search.
 
Using the appropriate table (CAN-DWBI-1 or CAN-DWBI-2), find the resulting Canadian Dumont-Willis-Beal Index Sum of Scaled Scores in the column labeled "Sum of CAN-DWBI SSS" in the Tables below and read across the row to determine the CAN-DWBI score, associated percentile rank, and 95% confidence interval (based upon the Standard Error of Estimate).  Be sure to use the "CAN-DWBI-1: VCI + PRI" table for the six Verbal Comprehension and Perceptual Reasoning subtests (you will see that a SSS of 60 equals a standard score of 100).  Use the "CAN-DWBI-2: WMI + PSI" table for the four Working Memory and Processing Speed subtests (you will see that a SSS of 40 equals a standard score of 100).
 
Estimates of overall abilities calculated in this way should always be clearly identified as CAN-DWBI scores in both text and tables of reports.  These scores must not be confused with the Full Scale IQ, although they may be more useful estimates of intellectual ability in some cases, for example, for some gifted children and for some children with relative weaknesses in Working Memory and/or Processing Speed.  For the latter group, the CAN-DWBIs may help avoid Dumont and Willis's Mark Penalty,[7] the depression of a measure of intelligence by a low score on a measure of a student's specific weakness.  Other children may score significantly higher on the WMI and PSI indices than on the VCI and PSI indices, which may mask important difficulties with conceptual thinking if the FSIQ is used without the CAN-DWBIs.
 
The equivalent tables for the U.S. WISC-IV and additional information about the Tellegen and Briggs formulas are posted at http://alpha.fdu.edu/psychology.

Canadian Dumont-Willis-Beal Index 1  (CAN-DWBI-1: VCI+PRI)

Sum of CAN-DWBI-1 SSS

CAN-DWBI-1 Score

Percentile Rank

95% Confidence Range

 

Sum of CAN-DWBI-1 SSS

CAN-DWBI-1 Score

Percentile Rank

95% Confidence Range

Min

Max

 

Min

Max

6

39

1

36

48

 

61

101

53

95

107

7

40

1

37

50

 

62

102

55

96

108

8

41

1

38

51

 

63

103

58

97

109

9

42

1

39

52

 

64

105

61

98

111

10

44

1

40

53

 

65

106

63

99

112

11

45

1

41

54

 

66

107

66

100

113

12

46

1

42

55

 

67

108

68

101

114

13

47

1

43

56

 

68

109

73

102

115

14

48

1

44

57

 

69

110

75

103

116

15

49

1

46

58

 

70

111

77

104

117

16

50

1

47

59

 

71

112

79

106

118

17

52

1

48

60

 

72

114

81

107

119

18

53

1

49

61

 

73

115

82

108

120

19

54

1

50

62

 

74

116

84

109

121

20

55

1

51

63

 

75

117

86

110

122

21

56

1

52

65

 

76

118

88

111

123

22

57

1

53

66

 

77

119

90

112

124

23

58

1

54

67

 

78

120

91

113

126

24

59

1

55

68

 

79

121

92

114

127

25

61

1

56

69

 

80

123

93

115

128

26

62

1

57

70

 

81

124

94

116

129

27

63

1

58

71

 

82

125

95

117

130

28

64

1

59

72

 

83

126

95

118

131

29

65

1

61

73

 

84

127

96

119

132

30

66

1

62

74

 

85

128

96

121

133

31

67

1

63

75

 

86

129

97

122

134

32

68

2

64

76

 

87

130

97

123

135

33

70

2

65

77

 

88

132

98

124

136

34

71

2

66

78

 

89

133

98

125

137

35

72

3

67

79

 

90

134

99

126

138

36

73

3

68

81

 

91

135

99

127

139

37

74

4

69

82

 

92

136

99

128

141

38

75

5

70

83

 

93

137

99

129

142

39

76

5

71

84

 

94

138

99

130

143

40

77

6

72

85

 

95

139

99

131

144

41

79

7

73

86

 

96

141

99

132

145

42

80

8

74

87

 

97

142

99

133

146

43

81

9

76

88

 

98

143

99

134

147

44

82

10

77

89

 

99

144

99

135

148

45

83

13

78

90

 

100

145

99

137

149

46

84

14

79

91

 

101

146

99

138

150

47

85

16

80

92

 

102

147

99

139

151

48

86

18

81

93

 

103

148

99

140

152

49

88

19

82

94

 

104

150

99

141

153

50

89

21

83

96

 

105

151

99

142

154

51

90

23

84

97

 

106

152

99

143

156

52

91

25

85

98

 

107

153

99

144

157

53

92

30

86

99

 

108

154

99

145

158

54

93

32

87

100

 

109

155

99

146

159

55

94

34

88

101

 

110

156

99

147

160

56

95

37

89

102

 

111

158

99

148

161

57

97

39

91

103

 

112

159

99

149

162

58

98

42

92

104

 

113

160

99

150

163

59

99

45

93

105

 

114

161

99

152

164

60

100

50

94

106

 

115

162

99

153

165

 

 

 

 

 

 

116

163

99

154

166

 

 

 

 

 

 

117

164

99

155

167

 

 

 

 

 

 

118

165

99

156

168

 

 

 

 

 

 

119

167

99

157

169

Canadian Dumont-Willis-Beal Index 2  (CAN-DWBI--2: WMI+PSI)

Sum of CAN-DWBI-2 SSS

CAN-DWBI-2 Score

Percentile Rank

95% Confidence Range

 

Sum of CAN-DWBI-2 SSS

CAN-DWBI-2 Score

Percentile Rank

95% Confidence Range

Min

Max

 

Min

Max

4

40

1

37

49

 

41

102

53

96

107

5

42

1

39

50

 

42

103

58

97

109

6

44

1

40

52

 

43

105

61

99

111

7

45

1

42

53

 

44

107

66

101

112

8

47

1

43

55

 

45

108

70

102

114

9

49

1

45

56

 

46

110

73

104

115

10

50

1

47

58

 

47

112

77

105

117

11

52

1

48

60

 

48

113

81

107

118

12

54

1

50

61

 

49

115

82

109

120

13

55

1

51

63

 

50

117

86

110

122

14

57

1

53

64

 

51

118

88

112

123

15

59

1

55

66

 

52

120

90

113

125

16

60

1

56

68

 

53

122

92

115

126

17

62

1

58

69

 

54

123

94

117

128

18

64

1

59

71

 

55

125

95

118

130

19

65

1

61

72

 

56

127

96

120

131

20

67

1

62

74

 

57

128

96

121

133

21

69

2

64

76

 

58

130

97

123

134

22

70

2

66

77

 

59

131

98

124

136

23

72

3

67

79

 

60

133

99

126

138

24

73

4

69

80

 

61

135

99

128

139

25

75

5

70

82

 

62

136

99

129

141

26

77

5

72

83

 

63

138

99

131

142

27

78

7

74

85

 

64

140

99

132

144

28

80

9

75

87

 

65

141

99

134

145

29

82

10

77

88

 

66

143

99

136

147

30

83

13

78

90

 

67

145

99

137

149

31

85

16

80

91

 

68

146

99

139

150

32

87

18

82

93

 

69

148

99

140

152

33

88

21

83

95

 

70

150

99

142

153

34

90

25

85

96

 

71

151

99

144

155

35

92

27

86

98

 

72

153

99

145

157

36

93

32

88

99

 

73

155

99

147

158

37

95

37

89

101

 

74

156

99

148

160

38

97

39

91

103

 

75

158

99

150

161

39

98

45

93

104

 

76

160

99

151

163

40

100

50

94

106

 

 

 

 

 

 


[1] Wechsler, D. (2004).  WISC-IV Canadian Manual Toronto: The Psychological Corporation.

[2] Dumont, R. & Willis J.O,  (2004). Use of the Tellegen and Briggs formula to determine the Dumont-Willis Indexes (DWBI-1 & DWBI-2 for the WISC-IV).  Available:  http://alpha.fdu.edu/psychology.

[3] Tellegen, A., & Briggs, P.  (1967). Old wine in new skins: Grouping Wechsler subtests into new scales.  Journal of Consulting Psychology, 31, 499-506.

[4] Prifitera, A., Weiss, L. G., & Saklofske, D. H. (1998).  WISC-III in context.  In A. Prifitera & D. H. Saklofske (Eds.)  WISC-III clinical use and interpretation: Scientist-practitioner perspectives (pp. 1-38).  San Diego: Academic Press.

[5] Kaufman, A. S. (1979).  Intelligent testing with the WISC-R. New York:  Wiley Interscience.

[6] Kaufman, A. S. (1994).  Intelligent testing with the WISC-III.  New York:  Wiley Interscience.

[7] Willis, J. O. & Dumont, R. P. (2002, pp. 131-132).  Guide to identification of learning disabilities (3rd ed.).  Peterborough, NH: authors.  [http://alpha.fdu.edu/psychology]

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