GENERATION OF 

 USE ESTIMATES 



Regression estimates of 

 use were not improved 

 by adding information 

 on one- and two-person 

 and local groups. 



The basic data from which use estimates were generated included information ob- 

 tained from registration cards completed by visitors entering the area (called X 

 variables) ; personal interviews on sampling days with entering visitors after they had 

 had an opportunity to register at the registration stations (Y variables); and personal 

 interviews on sampling days with visitors leaving the area (Z variables) . Several 

 analytical estimation procedures were tested to determine which one produced the most 

 precise estimates of use including: (a) registration information, (b) ratio estimation, 

 (c) stratified random-sampling estimation, and (d) simple and multiple regression 

 estimation. 



The target (or planned) population we wanted to estimate included all visitors to 

 the Mission Mountains Primitive Area. However, the sampled populations on which 

 analyses were based were slightly different from this target population because we 

 didn't sample: (a) The few winter and spring visitors, (b) users of lightly used and 

 unknown trails, (c) visitors who did not enter on established trails, and (d) users who 

 entered and left on sampling days during late evening and early morning hours (from 

 8 p.m. to 8 a.m.). Some indication of the effect of our decision not to sample during 

 these hours is the fact that about 11 percent more groups were interviewed upon leaving 

 than upon entering (412 vs. 370 groups). This was due primarily to early entry of 

 visitors into the area. A few groups probably entered so early and left so late that 

 they were missed entirely. In addition, some uses such as total use in visitor-days 

 were estimated in terms of how long people expeated to stay rather than how much time 

 they aatuatty spent in the area. 



Estimates of use were generated for 13 variables (see Appendix III), only three 

 of which developed as variables of primary importance. These three (called key 

 variables throughout this report) are (a) number of visitors (i = 1) , (b) use in 



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