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Table 8 Types and definitions of evidence classification and criterion used by each systematic review

From: Evaluation parameters for evidence-based practices for people with autism spectrum disorder: a narrative review of group and single-subject design studies

Systematic reviews Evidence classification/category Definition Criterion of empirical support
NAC (2009, 2015) Established Sufficient evidence is available to confidently determine that an intervention produces favorable outcomes for individuals on the autism spectrum. That is, these interventions are established as effective (a) ≥ 2 GD or 4 SSD studies with ≥ 12 participants for which there are no conflicting results or at least 3 group design or 6 SSD studies with a minimum of 18 participants with no more than 10% of studies reporting conflicting results. (b) GD and SSD may be combined. (c) Peer-reviewed studies with SMRS scores of 3, 4, or 5 pts. (d) Beneficial intervention effects for a specific target. (e) These may be supplemented by studies with lower scores on the SMRS
Emerging Although one or more studies suggest that an intervention produces favorable outcomes for individuals with ASD, additional HQ studies must consistently show this outcome before we can draw firm conclusions about intervention effectiveness (a) ≥ 2 GD studies or 2 SSD studies with ≥ 6 participants for which no more than 10% of studies reporting conflicting results. Conflicting results are reported when a better or equally controlled study that is assigned a score of ≥ 3 reports either (a) ineffective intervention effects or (b) adverse intervention effects; (b) GD and SSD may be combined. (c) Peer-reviewed studies with SMRS scores of 2 pts. (d) Beneficial intervention effects reported for one DV for a specific target. (e) May be supplemented by studies with lower SMRS’s scores
Unestablished There is little or no evidence to allow us to draw firm conclusions about intervention effectiveness with individuals with ASD. Additional research may show the intervention to be effective, ineffective, or harmful (a) May or may not be based on research. (b) Beneficial intervention effects reported based on very poorly controlled studies (scores of 0 or 1 on the SMRS). (c) Claims based on testimonials, unverified clinical observations, opinions, or speculation. (d) Ineffective, unknown, or adverse intervention effects reported based on poorly controlled studies
NPDC (2010, 2014) Evidence based Specifies that an intervention is identified as EBPs if supported by the number of studies specified in the “criterion” column (a) 2 HQ experimental or quasi-experimental design studies conducted by 2 different research groups, or (b) 5 HQ SSD studies conducted by 3 different research groups and involving a total of 20 participants across studies, or (c) there is a combination of research designs that must include at least 1 HQ experimental/quasi-experimental design, 3 HQ SSDs, and be conducted by more than one researcher or research group
Other practices with some support Some practices had empirical support from the research literature, but they were not identified as EBPs because it did not meet criteria established Subdivided into (1) idiosyncratic behavioral intervention packages: behavioral packages not replicated across studies (i.e., combinations of EBPs and other practices to create interventions to address participant’s individual and unique goals) and (2) other practices with empirical support: focused intervention that there was an insufficient number of studies documenting efficacy, or there was a sufficient number of acceptable studies conducted by only one research group, or still, there were a sufficient number of SSD studies, but there were not a sufficient number of total participants across studies
NCAEP (2020) Evidence-based practice Interventions that have clear evidence of positive effects with children and youth people with ASD (a) ≥ 2 HQ GD studies conducted by at least 2 different researchers or research groups, or (b) 5 HQ SSD studies conducted by 3 different investigators or research groups and having a total of at least 20 participants across studies, or (c) 1 HQ GD study and at least 3 HQ SSD studies conducted by at least 2 different investigators or research groups (across the group and single-case design studies)
Manualized Interventions meeting criteria Interventions that (a) are manualized, (b) have unique features that create an intervention identity, and (c) share common features with other practices grouped within the EBP classification
Practices with some evidence Focused intervention practices, which did not yet have sufficient evidence to meet criteria for an EBP, but they had some empirical support Not meeting criteria for EBP specially because there was an insufficient number of HQ studies providing support, few participants, or just one researcher or research group
  1. GD group design, SSD single-subject design, SMRS Scientific Merit Rating Scale, HQ high-quality, DV dependent variable