Interpretation of the SIPP: how should it be done?
Higher scores on SIPP-facets or SIPP-domains refer to more adaptive (and thus less pathological) capacities. The SIPP is a self-report questionnaire. The scores of a particular person therefore refer to how this person sees himself/ herself. T-scores are calculated, which are labeled as:
<30: very low
≥70: very high
First, you look at the severity (thus lower scores) of the personality pathology in comparison with the normal population:
- Inspect the domain (*) level. Any T-scores below 40 indicate impaired adaptive functioning, and any T-scores below 30 indicate severely impaired adaptive functioning.
- Within the domains with T<40, the next step is to look at the facet level. Which specific facets account (particularly) for the low score at the higher-order domain level?
Second, you compare these dimensions (either domains or facets) with T-scores lower than 40, with the clinical population data. This provides a sense of the clinical relevance.
- For example, if T=34 in comparison with normals, but T=41 in comparison with other clients, this indicates low to modest severity.
- However, if T=28 in comparison with normals, and T=32 in comparison with other clients, this indicates (very) high severity.
Third, you look at the healthy aspect (thus higher scores) of the patient’s personality:
- Follow the same hierarchical strategy as with the identification of pathology, but now you look at T-scores above 60 for strong capacities, and above 70 for very strong capacities. Do not use clinical population data to identify strong capacities, thus only normal population data.
(*) NB: These steps should be read as a recommendation instead of as the only right option; some clinicians prefer to start with interpreting the facet-level instead of taking the domain-level of starting-point.
Description of facets and domains