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Effects of the avidity bias survey estimates of fishing effort and economic value


This paper describes the avidity bias (the disproportionate representation of avid anglers) in intercept surveys and shows how bias-corrected estimates of mean and variance can be computed. It compares bias-corrected participation rates with actual participation rates reported by California anglers in an economic survey conducted as a mail follow-up to a random telephone canvass, and in an on-site intercept survey. Although both samples contained this bias, it was much more pronounced in the on-site survey than in the mail survey. The findings indicate that failure to correct for avidity bias results in inflated estimates of per capita fishing expenditures and consumer surplus as well as fishing effort. In general, the effect of the avidity bias on estimates of economic value depends not only on the extent of the bias, but also on the relationship between angler expenditures and avidity, and on the functional form of the travel cost model underlying estimates of consumer surplus.

Source: Thomson, C.J. 1991. "Effects of the avidity bias survey estimates of fishing effort and economic value." In: Creel and angler surveys in fisheries management, D. Guthrie et al., eds. American Fisheries Society Symposium, 12: 356-366.

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