CANS item responses cannot be averaged or summed into domain scores like “Strengths,” because the data is nominal, not continuous, interval, or ordinal. The data would be ordinal data, but for a score of 1 that can carry multiple uncategorized meanings. CANS has a 4-point scale (0, 1, 2, or 3) for each item.

Midpoint anomaly

It’s the score of 1 that clearly defines CANS responses as nominal.

• 1 can mean:
  • preventative services are required; or
  • stakeholder disagreement (parent, child, treatment team members,  …); or
  • more assessment time is required.

Anyone analyzing a dataset has no clue which of the three subcategory response choices were meant by the rater(s). As such, you might not even call the data nominal.

With more time and evaluation on each clinical case, some of these categorized-1-scores should really be a 3, meaning “hey, after more assessment time, we realize he’s really suicidal, is not contracting for safety, has a plan, has access to a gun, and it’s life threatening.”

And some of these categorized-1-scores are more accurately 0, meaning “we’ve investigated further and conclude that he’s not even depressed and we’re convinced he’s never been suicidal, and has no current thoughts or intentions.”

Shared vision and Pre-measurement triangulation

This midpoint anomaly is made infinitely more complicated by Lyons’ belief in “shared visions” and “pre-measurement triangulation” that requires all stakeholders to work together to complete the CANS, not independently, but as a collective group-think exercise. It comes from Lyons’ theory of human services that he calls Communimetrics (Lyons, 2009).

“The theory of communimetrics holds that the primary role of measurement in human service enterprises is to communicate…. The notion that measurement is communication within human service enterprises shifts important aspects of this activity away from the domain of scientists and into the domain of managers. Such a shift requires substantial simplification in order for individuals without scientific training to utilize measurement processes….

“These constitutive theories fit perfectly within the goals of human service enterprises—to establish a shared vision of the needs of people served, and to monitor the impact of interventions on these needs over time….

“The concept of creating and measuring a shared meaning can be understood as engaging in a pre-measurement triangulation process. If the multiple parties involved in the human service enterprise participate in the creation [of the ratings] …, then the value of triangulation is preserved—multiple perspectives are represented. But since only one measure results, the burden, expense, and analytic complexity of both analysis and interpretation is dramatically simplified. This simplification makes the use of data from these measures far more widely accessible to individuals who may not be sufficiently sophisticated in statistics or program evaluation to analyze, report, and interpret data collected using traditional triangulation strategies….

“This is usually accomplished by capturing information from the multiple service providers involved and then analyzing each perspective separately. Integration can only occur at the interpretation of findings. This process can be both cost- and labour-intensive, and allows for the introduction of single and/or group decision-making biases depending on the manner in which the team operates….

“Of course, pre-measurement triangulation through the use of a communimetric measurement approach has limitations. It is always possible that someone who completes the measure fails to actually involve others in its production. This problem is reduced by making the measure an active part of the intervention itself and ensuring that all parties expect to see it and participate in its creation….

“It is also possible that users with different perspectives cannot come to an agreement. Although this phenomenon does happen, it has been our experience that it is uncommon. The CANS was used more than one million times worldwide in 2009, and the anecdotal experience of those using it suggest that significant contention arises in no more than 1% of cases. However, when disagreements are not resolvable, the “1” rating (indicating watchful waiting/prevention) is recommended, so that the parties can monitor the need and see over time who has the more accurate perspective” (Obeid & Lyons, 2011, p. 67-77)

Therefore, the score of 1 can be used when team members, family members and the child, who are supposed to be sitting around together, debating and having their voices heard, do not agree, for example, whether the substance abuse problem is urgent enough to require “immediate or intensive” intervention (3), or the problem can be handled as a 2, with normal out-patient intervention. Instead of categorizing these disagreements as, maybe, a 2.5, (or leaving it blank) raters are required to put it down as a 1.

It’s not clear that any jurisdiction or user of CANS has ever been able to accomplish the tool-required pre-measurement triangulation. Lyons boasts that he knows from the million children assessed each year that it can happen. It’s more probable that the pre-measurement triangulation meetings never happen or would take days to come to consensus on over a hundred ratings. An adolescent, for example that is abusing substances and not ready to change, will insist on a low rating and others will insist on a high rating. This is what the initial phase of much substance abuse treatment focuses on, increasing readiness to change and admitting that one has a problem. If treatment cannot start until we do the assessment and all agree on everything, a lot of consumers will likely suffer.

CANS data is nominal data and the summary data reported on CANS is suspect.