psychometric development of a new inventory to assess symptoms across the spectrum of autism

Presented by

Peter D. Marle, B.A.

Psychometric Development of a New Inventory to Assess

Symptoms Across the Spectrum of Autism

Coolidge Autistic Symptoms Survey

Presented By Peter D. Marle, B.A.


• History and Popular Conceptions of Autism

• Possible accounts written as early as the 16th century (Martin Luther)

• First psychiatric evaluations – early 20th century (De Sanctis, Earl, & Potter)

• First scientific research – 1943 (Leo Kanner) and 1944 (Hans Asperger)

• Comparing Kanner’s and Asperger’s narratives

• Both differentiated autistic behaviors in the children from schizophrenia

• Children studied had milder forms of autism

• Asperger emphasized the malicious behaviors of the children

• Kanner suspected the origin of autism to come from cold parents


• Controversies

• Bettelheim and “refrigerator mothers”

• Rimland

• Jenny McCarthy

• Vaccinations causal to autism?


• History of the Diagnosis of Autism

• Diagnostic and Statistical Manual of Mental Disorders (DSM; 1952)

• No diagnosable autistic condition

• Most synonymous diagnosis: Schizophrenic reaction, childhood type

• DSM-II (1968)

• Largely unchanged regarding the diagnosis of autism

• DSM-III (1980)

• Infantile autism

• DSM-III-R (1987)

• Autistic disorder

• Pervasive developmental disorder – not otherwise specified


• History of the Diagnosis of Autism

• DSM-IV (1994)

• Autistic Disorder

• Childhood disintegrative disorder

• Asperger’s Disorder

• Pervasive developmental disorder – not otherwise specified

• DSM-IV-TR (2000)

• Largely unchanged regarding the diagnosis of autism

• DSM-5 (2013)

• Autism Spectrum Disorder

• Continuum, with three degrees of severity


• Proposed DSM-5 Diagnostic Criteria for Autism Spectrum DisorderA. Persistent deficits in social communication and social interaction across contexts,

not accounted for by general developmental delays

B. Restricted, repetitive patterns of behavior, interests, or activities

C. Symptoms must be present in early childhood

D. Symptoms together limit and impair everyday functioning


• Proposed DSM-5 Diagnostic Criteria for Autism Spectrum DisorderA. Persistent deficits in social communication and social interaction across contexts,

not accounted for by general developmental delays, manifested by all three of the following:

1. Social Interactions: abnormal social approach, conversation, reduced sharing of interests and emotions

2. Nonverbal Communication (includes verbal): abnormal eye contact, body language, facial expressions, and gestures

3. Peer Relationships: adjustment of behavior to suit social contexts, imaginative play, seems not interested in people


• Proposed DSM-5 Diagnostic Criteria for Autism Spectrum DisorderB. Restricted, repetitive patterns of behavior, interests, or activities as manifested by at

least two of the following:

1. Stereotypies: repetitive speech, motor movements, use of objects

2. Routine: need for routine, patterns of behavior, resists change

3. Fixations: fixated interests

4. Sensory Integration: hyper and/or hypo-reactive to environmental stimuli


• Current Methods for Diagnosing Autism

• Prevalence rate between 1:88 and 1:2000 (males 4 x more likely)

• Combination of clinical observation, use of diagnostic tools, and parental reports

• Current diagnostic tools

• Autism Diagnostic Interview-Revised

• Autism Diagnostic Observation Schedule

• Childhood Autism Rating Scale


• Need for an Updated Diagnostic Tool

• Current tools may soon be outdated

• Development of the Coolidge Autistic Spectrum Survey

• Created to examine similarities between Asperger’s disorder and high functioning

autism (2007)

• Another study later investigated the differentiation of milder forms of ASD and

schizoid personality disorder traits (in press)


• Purpose

To redesign the CASS in order to provide coverage for the new criteria in DSM-5 and to

extend the lower age range of the CASS to approximately 2 to 3 years

• Hypotheses

1. A 1-component solution (as determined by principal components analysis) would best fit

the structures of the new 83-item CASS and 39-item CASS-T (based on a previous study);

although, DSM-5 diagnostic criteria for ASD may suggest multiple components.

2. The new CASS and CASS-T would show good internal reliability (Cronbach’s α ≥ .80).

3. The surveys would have an adequate split-half reliability (r ≥ .80).

4. The surveys would significantly differentiate among children with

a) milder forms of autism (e.g., Asperger’s disorder and high-functioning autism)

b) moderate-to-severe forms of autistic spectrum disorders

c) no diagnoses (i.e., a group-matched control group)

5. There would be a strong, positive correlation between the CASS-T and the CASS means.


Table 1Participant Data for Mild ASD, Moderate-to-Severe ASD, Group-Matched Control Group, and Full Dataset n

(% male)* Age

Range* Age

(M, SD)% in

TherapyTherapy Length(Months; M, SD)

* Age Dx(M, SD)

Mild ASD 22 (77%) 6 – 16 (9.6, 2.5) 52% (30.5, 21.8) (6.4, 3.1)M-S ASD 23 (83%) 5 – 16 (9.2, 3.3) 81% (60.1, 37.6) (3.0, 1.6)Control 22 (59%) 5 – 17 (9.6, 3.9) 0% --- ---Full DS (CASS-T) 88 (63%) 5 – 17 (9.9, 3.5) 38% (45.4, 32.6) (4.7, 3.1)Full DS (CASS) 86 (63%) 5 – 17 (9.9, 3.6) 34% (48.2, 33.7) (4.6, 3.0)Note. M-S = Moderate-to-Severe. DS = Dataset. Dx = Diagnosed. * in years.

• Participants• Materials

• Informed Consent Form

• Demographic Sheet

• 39-item CASS-T (Retrospective)

• 83-item CASS

• Procedure• All data were collected with approval from the University’s institutional review board

• Packets were either

• hand-delivered to parents via a CITI-trained researcher (i.e., Peter D. Marle) or

• given in an electronic format (via a secure online survey host; i.e., PsychData.com)

• Packets took approximately 30 min to complete

• Participants were given the option of returning the materials via a SASE or returning

the materials to the CITI-trained researcher


* Supplemental Information on Component Solutions

Hypothesis 1

A 1-component solution would provide the best fit for the CASS and the CASS-T

(accounting for at least 50% of the variance)

• 83-item CASS

• A 1-component solution accounted for about 52% of the variance

• 39-item CASS-T

• Either a 4-component (total variance explained = 65.5%) or

5-component solution (total variance explained = 69.5%) best fit the data

Table 2Cronbach’s α Computations for the CASS-T 4- and 5-Component Solutions

4-Component Solution 5-Component Solution

Component # Items α # Item Overlap # Items α

1: DSM Dx Criteria 20 .96 14 19 .97

2: Physical Contact 9 .91 6 7 .90

3: Development 6 .83 4 4 .79

4: Sensory Issues 4 .91 4 4 .91

5: Stereotypy/Humor -- -- 0 5 .84

Note. For all analyses, n = 88. # Item Overlap refers to the number of items in the 5-component solution that also appear in the respective 4-component solution component.


Hypothesis 2

The new CASS and CASS-T would show good internal reliability (Cronbach’s α ≥ .80)

• 83-item CASS

• Cronbach’s α = .99 (n = 86)

• 39-item CASS-T

• Cronbach’s α = .97 (n = 88)

Table 2Cronbach’s α Computations for the CASS-T 4- and 5-Component Solutions

4-Component Solution 5-Component Solution

Component # Items α # Item Overlap # Items α

1: DSM Dx Criteria 20 .96 14 19 .97

2: Physical Contact 9 .91 6 7 .90

3: Development 6 .83 4 4 .79

4: Sensory Issues 4 .91 4 4 .91

5: Stereotypy/Humor -- -- 0 5 .84

Note. For all analyses, n = 88. # Item Overlap refers to the number of items in the 5-component solution that also appear in the respective 4-component solution component.


Hypothesis 3

The CASS and CASS-T would have adequate split-half reliabilities (r ≥ .80)

• 83-item CASS

• r(87) = .98, p < .001

• 39-item CASS-T

• r(90) = .95, p < .001


Contro

l

Mild

ASD

Mod

erat

e-to

-Sev

ere

ASD

Contro

l

Mild

ASD

Mod

erat

e-to

-Sev

ere

ASD

1

2

3

4

CASS Mean

CASS-T Mean

Pos

sibl

e M

eans

ran

ged

from

1

(Str

ongl

y F

alse

) to

4 (

Str

ongl

y T

rue)

Figure 1. Comparison of CASS and CASS-T group means. 95% CIs are given.

Hypothesis 4

There would be significant differences among the group means for the CASS and CASS-T

a) the moderate-to-severe autism group would have the significantly highest mean,

b) the mild autism group would have the second highest mean, and

c) the group-matched control group would have the significantly lowest mean

• 83-item CASS

F(2, 64) = 199.93,

p < .0005; η2 = .86

• 39-item CASS-T

F(2, 64) = 165.56,

p < .0005; η2 = .84


1 1.5 2 2.5 3 3.5 40

1

2

3

4

Control

Mild ASD

Moderate-to-Severe ASD

CASS Mean

CASS

-T M

ean

Figure 2. Scatterplot of CASS and CASS-T means marked by group.

Hypothesis 5

There would be a strong, positive correlation between the CASS-T and the CASS means

• Correlation coefficient

r(92) = .89, p < .0005


Hypothesis 1

A 1-component solution would provide the best fit for the CASS and the CASS-T

(accounting for at least 50% of the variance)

• 83-item CASS

• A 1-component solution accounted for about 52% of the variance

• Hypothesis supported

• 39-item CASS-T

• Either a 4-component (total variance explained = 65.5%) or

5-component solution (total variance explained = 69.5%) best fit the data

• Hypothesis not supported

1. DSM-5 diagnostic criteria for ASD, sans sensory issues

2. Physical contact

3. Developmental milestones

4. Sensory issues

5. The 5-component solution added a stereotypies and humor component


Hypothesis 1• 39-item CASS-T

• DSM-5 diagnostic criteria for ASD, sans sensory issues

• Physical contact

• Developmental milestones

• Sensory issues

• The 5-component solution added a stereotypies and humor component

• DSM-5 Criteria• Social Interactions• Nonverbal Communication • Peer Relationships

• Stereotypies• Routine• Fixations• Sensory Integration

} manifested by all three

} manifested by at least two


Hypothesis 2

The new CASS and CASS-T would show good internal reliability (Cronbach’s α ≥ .80)

• 83-item CASS

• Cronbach’s α = .99 (n = 86)


• 39-item CASS-T

• Cronbach’s α = .97 (n = 88)


• Alphas too high?


Hypothesis 3

The CASS and CASS-T would have adequate split-half reliabilities (r ≥ .80)

• 83-item CASS

• r(87) = .98


• 39-item CASS-T

• r(90) = .95


• Comparing split-half reliability and Cronbach’s α


Contro

l

Mild

ASD

Mod

erat

e-to

-Sev

ere

ASD

Contro

l

Mild

ASD

Mod

erat

e-to

-Sev

ere

ASD

1

2

3

4

CASS Mean

CASS-T Mean

Pos

sibl

e M

eans

ran

ged

from

1

(Str

ongl

y F

alse

) to

4 (

Str

ongl

y T

rue)

Figure 1. Comparison of CASS and CASS-T group means. 95% CIs are given.

Hypothesis 4

There would be significant differences among the group means for the CASS and CASS-T

a) the moderate-to-severe autism group would have the significantly highest mean,

b) the mild autism group would have the second highest mean, and

c) the group-matched control group would have the significantly lowest mean

• 83-item CASS

• F(2, 64) = 199.93,

p < .0005; η2 = .86


• 39-item CASS-T

• F(2, 64) = 165.56,

p < .0005; η2 = .84



1 1.5 2 2.5 3 3.5 40

1

2

3

4

Control

Mild ASD


CASS Mean

CASS

-T M

ean


Hypothesis 5



• r(92) = .89, p < .0005



1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.20

1

2

3

4

Control

Mild ASD


CASS Mean

CASS

-T M

ean


Only midpoints given.

Hypothesis 5



• r(92) = .89, p < .0005



1 1.5 2 2.5 3 3.5 40

1

2

3

4

Control

Mild ASD


CASS Mean

CASS

-T M

ean


Midpoints with 1 standard deviation projection given.

Hypothesis 5



• r(92) = .89, p < .0005



• This study did not investigate the differentiation of moderate ASD• Future research into the CASS and the CASS-T should explore this.

• This study used parent-as-respondent data• Cost vs. accuracy/error

• Small sample size for the PCA• This study served as a preliminary component structure assessment of the surveys.

• Future PCA with a larger pool of participants is recommended.

• Test-retest reliability was not assessed• This study assessed split-half reliability.

• Future studies should investigate time-based reliability.


• Sensitivity and specificity of surveys not assessed• Future research investigating the accuracy of the surveys to accurately categorize ASD

into groups, as well as to accurately assess any non-ASD diagnosis.

• Gender and age differences regarding the surveys should be analyzed• Future research should explore differences in item responses by age and gender.

• Sensory integration disorder and the CASS• Because of the possible current trend of misdiagnosing children with an ASD who may

only have sensory integration problems, future research with the CASS should assess

the differentiation of these children.


Thank you!

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