Table 3 
Category speed (m/min)| car walking 
1. Base camp parking place 207 + 
2. Parking place 1)-plot 17 * 
3. Plot-parking place 1) 42 * 
4. Parking place 1) - pp. 2) 207 + 
  
  
  
  
  
  
For item 2) it was necessary to use a formula, which considers a 
gradually reducing walking speeü when approaching *he field plot. The 
average walking speed is calculated from 
27d 
8 = 170 + à m/minute, in which d = distance (Trân-Châu-Lam, 1977). 
In general, the number of enumerated plots per crew-day varied between 
9 and 11. 
In calculating the field time for the required number uf plots, time is 
left over, as exactly eight hours per day is not always consumed. In 
Table 4, Column 4, this time is given as a minus time. 
  
  
  
  
Table 4 Man-days in field and office for four sampling methods 
number of man-days 
Sampling method - field office | total 
enumeration travel over from field (rounded 
of) 
Unrestricted 3.3 13.2 Yas 8.8 18 
Stratified 1.9 7.4 - 0.5 18.3 23 
Two-stage PPS 2.8 6.4 - 0.8 9.5 27.8 
[Two-phase 1.0 4.3 - 0.7 8.3 13 
  
  
  
  
  
  
  
  
The number of man-days, as given in Table 4, Column 6, are in fact not yet 
suitable to permit a decision on the most efficient method. For the two- 
phase method, an optimum ratio between photo/field plots was calculated 
using a cost ratio. Therefore the cost factor should be considered for 
the other methods also. Assuming that a field man-day costs twice as much 
as an office man-day, the data of Table 5 in office man-day units are more 
suitable for comparison. 
  
  
Table 5 Comparison of sampling methods, using office man-day units 
Sampling method office man-day-units 
Unrestricted (3.3 + 13.2 - 2.5) 2* 88 368 
Stratified (1.9 * 74 -0.5) 2-183 * 359 
Two-stage PPS (28* 64-08) 2-4 875255 
Two-phase (L0 + 43-0.) 2*4 7565 168 
  
  
  
  
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1953