Tests of Dyslexia (TOD)

• The components of the TOD can be used by a variety of clinicians and educators. For example, a classroom teacher may administer the TOD-Screener and complete the Teacher Rating Scale.
• Reading specialists, specialist teaching assessors, psychologists, and speech and language therapists are best suited to administer the TOD-Early or the TOD-Comprehensive due to their advanced coursework and experience with standardised tests.
• Interpretating test results requires a higher level of skill. For that reason, while a broader range of individuals can administer the test, interpretating results requires a knowledge of dyslexia and formal training in test administration, scoring, and interpretation.

Examiners should use only those tests for which they have the appropriate training and expertise. See Hogrefe's guidelines here or contact us to discuss.

Yes, there is an online video training programme available. Find further information and register here.

Yes, as of 07/05/24 the TOD has been approved by SASC. For details and guidance, please visit the SASC website. 

Following consultations with UK distributors and SASC, Western Psychological Services – the publisher of the new Tests of Dyslexia – has produced ‘British English’ versions of the TOD Screener Print Response Booklets. This decision was made in order to ensure the best possible testing experience for UK-based SpLD assessors; however please rest assured that continuing to use the forms originally supplied will not affect the results of an assessment. Please see the provided recommendations PDF (British English user guide) for information.

The new Screener response forms are now available and included in the kits sold by Hogrefe. Please note that there are no new norms – the normative data and all other TOD materials has not changed.

The online version of the TOD-S will continue to be available only in US English; please have a look at the British English User Guide to fully understand the changes and implications in choosing between the online US English or paper British English versions of the test.

If you have any questions, please contact us to discuss.

The rating scales included in the TOD-C, TOD-E, and TOD Combination kits are only available on the WPS Online Evaluation System™ (OES) at platform.wpspublish.com. Once you use the activation code on the OES, you can print out any of the Parent, Teacher, or Self-Rating Forms at no extra cost and as many times as you want if you prefer to administer any forms on paper. However, you still have to score the response forms online, which gives you access to beneficial reporting options.

No. The print screening materials are included in the TOD-Combination Kit, TOD-Early Kit and TOD-Comprehensive Kit.

TOD-E is intended for children ages 5-9 who are not yet reading connected text. This allows the assessor to gather the information they require, with testing materials at the correct skill level for the child.

The TOD-S is available as an online kit for remote administration (in US English). Click on the ‘Electronic’ tab on the TOD page of our webshop and select item 5506500 to add the TOD-S Online Kit to your cart. The TOD-S paper and pencil kit is not required. 

To administer the TOD-E or the TOD-C online, it is necessary to purchase the relevant kit plus the digital easels, which are under the Electronic tab. Test Administrators can use these digital easels for remote administration, but paper materials, record forms, and response booklets are still required. The test is then scored via the WPS Evaluation System platform.

See WPS’ remote administration video for more information on how this works. This article also outlines how to use the TOD-Screener remotely. 

The TOD-S can be administered digitally on the WPS OES and scored automatically or can be administered on paper. The TOD-C and TOD-E can only be administered on paper (although pdf easels are available for remote/digital administration, responses are recorded/scored on a paper record form). When administered on paper, the TOD-S, TOD-C, and TOD-E can be hand-scored or scored on OES for free. This free online scoring and reporting provides a convenient alternative to hand-scoring as well as an interpretive score report and access to a customisable intervention report.

The TOD is far more comprehensive of an assessment than the WRIT and designed to capture most of the important abilities relevant to dyslexia. In comparison to the Verbal Scale on the WRIT, there are two vocabulary measures on the TOD. In comparison to the Visual Scale on the WRIT, there are two fluid reasoning tests on the TOD, so similar constructs are being measured by both tests. The authors of the TOD do not really distinguish between the hypothetical concepts of ability and attainment as both are influenced by each other. Abilities can change as one attains more knowledge. The reasoning tests may, however, be viewed as a measure of reasoning ability, whereas the vocabulary tests are more of a reflection of attainment and educational experience. The TOD was primarily designed to measure the linguistic risk factors and the reading and spelling abilities that are most impacted by dyslexia.

The answer to this question is complicated and requires some context. Reliability and validity evidence occurs over time and from multiple studies and methodologies. It cannot be defined by single scores. Expert recommendations for interpreting reliability and validity estimates are produced by statistical equations.  

Reliability estimates are assumed to reflect the percentage of systematic variance in a test (vs. error) and can be calculated using statistical equations. The two most common reliability formulae are Cronbach’s Alpha and Spearman-Brown. Both yield coefficients designed to estimate the magnitude of the linear relationship between two variables, perhaps two versions of the same test. The most common correlational statistics assess relationships between either two interval-level variables (i.e., the Pearson Product Moment Correlation Coefficient) or two ordinal variables (i.e., Spearman’s Rho). Authors of tests and measurement texts (e.g., Sattler, 2018) provide criteria for interpreting these reliability coefficients (after Murphy & Davidshofer, 2005).  

Values above .90 are considered high/excellent; .80 to .89, moderately high or good; .70 to .79, moderate or fair; .60 to .69 low or poor; and .00 to .59, very low. Reliability coefficients set the limits on validity; for example, the square root of a reliability coefficient of a test defines the maximum predictive validity of that instrument. 

Validity is traditionally defined as the extent to which a test does what it was designed to do and, like reliability, is typically operationalised using correlation coefficients. Understanding the conceptual nature of “validity” is more complicated than reliability. Tests are valid for particular purposes. For example, validity coefficients address the extent to which a test assesses the construct it was created to address.  

Thus, construct validity is determined in part by how strong the correlation coefficient is between the test in question, say a newly developed test, and an established instrument that measures similar skills. In addition, validity data can inform prediction, i.e., how well a test predicts some criterion of interest. As an example, intelligence tests are often used to predict academic achievement. Across many studies reported in test manuals and in the general literature, these validity coefficients typically range from about .40 to .70, indicating that the percentage of the variance accounted for in achievement by intelligence ranges from about 16% to 49%.  

Reliabilities for the TOD tests and composites are typically good (i.e., greater than .80), as reported in the TOD Manual. Similarly, validity estimates are good also. For example, the TOD-C Dyslexia Diagnostic Index is a strong predictor of the probability of dyslexia.  

In summary, data generally support the reliability of the TOD indexes, composites, and tests and the validity of these scores for their intended purposes. Consequently, examiners can have confidence in the TOD scores.  

Yes, all TOD-Comprehensive tests go through 89 years, 11 months.

The TOD has US norms. 2,518 individuals aged 5 to 89 participated in the standardisation and validation studies. The TOD normative samples are TOD-C child (n = 1,401); TOD-C adult (n = 342); and TOD-E (n = 347). The TOD-S was taken by individuals in each of the three samples and serves as the basis for the TOD-S standardisation. Each sample closely matches US Census data based on gender, race/ethnicity, parents’ educational level, and geographic region. The remaining individuals made up the clinical validation samples and had a reading disability and/or other clinical diagnosis.

Clinical psychologists can use the TOD as part of a diagnostic assessment that may or may not identify dyslexia. They should work within the boundaries of recommendations from their regulatory bodies such as the HCPC and the BPS. If writing a diagnostic report for an individual of any age that may be used as evidence for submission for an application for the Disabled Students' Allowance in Higher Education, they must adhere to the SASC Report formats and SASC-approved test lists (these lists now include the TOD).

Yes, as TOD is approved by the SpLD Assessment Standards Committee (SASC), this means it can be used in assessing for access arrangements per the Joint Council for Qualifications (JCQ). Some professional organisations publish guides to using tests in access arrangements but there is no one set of specific rules or guidance.