Survey Response Data Overall, 32,077 total responses were received, of which 23,343 were determined usable—a number considerably higher than the 5,452 responses used in the 2008-09 practice analysis. However, it is impossible to determine what these numbers represent in terms of a fixed response rate; instead, the rate must be represented as an estimate within a range. There are two reasons for this complication. First, the number of social workers notified of the survey in eight Canadian provinces and California is unknown. ASWB estimates that 50,000 social workers may have been invited to participate in those jurisdictions not directly surveyed by HumRRO, but because a definitive number is not known it is impossible to estimate response rates for this population.