Can language acquisition be facilitated in cochlear implanted children? Comparison of cognitive and behavioral psychologists’ viewpoints

Table 1 Levels of evidence in medical research

Level of evidence	Study design
Level I	Systematic review (with homogeneity) of RCTs
	RCT with statistically significant difference or narrow confidence intervals
Level II	Low quality RCT (e.g., < 80% follow-up)
	Cohort study or other Prospective comparative study
	Systematic review of cohort studies
Level III	Case-control study or other Retrospective comparative study
	Systematic review of case-control studies
Level IV	Case series
	Poor quality case-control studies
Level V	Expert opinion
	Narrative reviews

Adopted from URL: http://www.cebm.net. RCT: Randomized control trial.