Table 2 .--Number of groups interviewed by stratum 



ocratuiu 

 number : 



Eu Lenng 

 only 



• Leaving 

 only 



Both entering 

 and leaving 



• At least 



• once 



1 



21 



39 



142 



202 



2 



16 



16 



81 



113 



3 



9 



26 



47 



82 



4 



3 



2 



7 



12 



5 



3 



3 



25 



31 



6 



4 



10 



9 



23 



7 



2 



4 



1 



7 



Totals 



58 



100 



312 



470 



The registration rate was depressed by stratum 7 (fall weekends on lightly and 

 moderately used trails) where only seven groups were contacted, none of whom had 

 registered. Registration rates, by stratum, were: 



Estimated Standard 

 registration rate error 3 



(Feroent) 



SUMMER 

 Stratum 



1 69 2 



2 76 4 



3 68 6 



4 83 20 



FALL 

 Stratum 



5 58 9 



6 57 10 



7 



Summer strata pooled^ 74 7 



Fall strata pooled^ 41 19 



All strata pooled^ 65 6 



Use was even more heavily concentrated on a few trails than had been expected; 

 as a result of this and the greater sampling intensity for heavy-use strata, 93 

 percent of all interviews occurred on two trails. Only five trails yielded five or 



^A confidence interval of plus or minus one standard error around the estimated 

 mean will contain the true mean about two-thirds of the time. Plus or minus 2 standard 

 errors will contain the true mean about 95 percent of the time. See Appendix II for the 

 formula (from Cochran, 1963, section 6.11) that was used to calculate standard errors. 



16 



