TILLS Technical Manual

This concise manual presents the powerful research and technical data behind the Test of Integrated Language and Literacy Skills™ (TILLS™). Professionals will find clear answers to frequently asked questions about the technical data as they learn the specifics of TILLS development and field testing and the composition of the normative sample.

Full chapters are devoted to the validity of TILLS, the reliability of TILLS, and the evaluation and reduction of test bias. Readers will get valuable information on

• test development using item response theory (IRT) procedures
• measurements of validity for each of the three purposes of TILLS
• evidence of additional aspects of construct validity, including confirmation that TILLS scores reflect age-related change and measure skills at both the sound/word and sentence/discourse levels
• the documenting of patterns of relative strengths and weaknesses and tracking change over time
• TILLS sensitivity and specificity levels, broken down into 9 age bands meaningful to the development of language and literacy skills
• strong reliability evidence for intra-class stability, inter-scorer reliability, and test-retest reliability
• the assessment process to remove or minimize item-level bias and subtest-level bias
• when to adjust cut scores for identifying language and literacy disorders

With this comprehensive resource on the unparalleled research behind TILLS, professionals will be confident that their language and literacy assessments will be completed with an extensively tested, psychometrically sound tool.

Table of Contents

• Normative Sample, Test Development, and Standardization of the TILLS

Criteria for Inclusion in the Normative Sample

Composition of the Normative Sample

Recruitment and Training of Test Administrators During Standardization

Test Development

Field Test 1

Field Test 2

Field Test 3

Frequently Asked Questions

• Validity of the TILLS

Validity for Purpose 1: Identifying Language and Literacy Disorders

Identification of Language and Literacy Disorders at Different Ages

Results for Subgroups of Students with Language Disorders

Sensitivity to Students at Risk for but Not Identified as Having Language and Literacy Disorders

Validity for Purpose 2: Profiling Strengths and Weaknesses

Students with Language and Literacy Disorders versus Typically Developing Peers

Patterns of Strengths and Weaknesses for Different Diagnostic Groups

Validity for Purpose 3: Tracking Change Over Time

Determining True Gains or Losses

Other Aspects of Construct Validity

Evidence that TILLS Scores Reflect Age-Related Change

Evidence that TILLS Measures Skills at the Sound/Word and Sentence/Discourse Levels

Concurrent Validity

Frequently Asked Questions

• Reliability of the TILLS

Intraclass Reliability

Testmdash;Retest

Reliability

Interrater Reliability

Measuring Students’ Abilities Reliably

Frequently Asked Questions

• Evaluation and Reduction of Test Bias

Statistical Evaluation of Item Bias

Assessment of Item-Level Bias

Assessment of Subtest-Level Bias

Implications of Score Differences for Interpreting TILLS Results

Frequently Asked Questions

References

Appendix Contributors to TILLS Development and Standardization