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CPS2042 Anna Christine D. et al.
               navigation device, and (ii) modified  track data where plot boundaries were
                                                  8
               digitized on Google Earth Pro. A GIS software named QGIS was used for data
               processing.

               3.  Results
                   Two sets of weights were calculated for the sample subplots based on each
                                                                     9
               source of area measurement—unmodified and modified  data.  These weights
               were used to produce alternative direct estimates of the total area planted in
               rice  alongside  calculating  corresponding  SE,  95%  confidence  intervals  and
               design effects.
               Table 3: Standard Error, Coefficient of Variation, and Design Effects of Estimates
               of Total Area Planted in Rice Paddy in m based on Area of Sample Plots from
                                                      2
               Unmodified Track Data

                                                         95% confidence interval
              Domain/Stratum   Area, m   2  SE    CV                          DEFF   No. of
                                                         Lower       Upper         observations

              Savannakhet   2,700,047,316   509,013,893   0.189  1,685,814,995   3,714,279,638   6.25   136
              IRRI+GlobCover   1,092,874,253   112,474,296   0.103   868,764,326   1,316,984,181   0.38   105
              IRRI           44,413,015   12,865,940   0.29   18,777,070   70,048,961   0.08   16
              GlobCover     804,851,923   203,242,057   0.253   399,883,285   1,209,820,561   1.73   13
              Other         757,908,125   452,738,125   0.597   0   1,660,008,531  10.98   2

              Ang Thong     292,337,345   40,269,296   0.138   210,408,846   374,265,843   1.69   104
              IRRI+GlobCover   274,834,018   39,838,268   0.145   193,782,453   355,885,582   1.62   82
              IRRI            2,779,591   976,108   0.351   793,684   4,765,498   0.03    8
              GlobCover      14,723,736   5,794,467   0.394   2,934,805   26,512,667   0.71   14

              Thai Binh     474,230,049   45,807,978   0.097   382,631,336   565,828,761   4.34   256
              IRRI+GlobCover   446,207,926   45,109,146   0.101   356,006,614   536,409,237   3.97   220
              IRRI             110,039    19,651   0.179   70,744     149,334   0         8
              GlobCover      27,912,084   7,970,911   0.286   11,973,262   43,850,906   0.92   28







               8  Field staff were asked to identify all obstructions and draw the correct boundaries of the plot
               on the printed map which was factored into the digitization process.
               9  Given the greater quality control involved in measuring the modified track area, the values are
               considered more accurate than the unmodified track data. Hence, the subplot weights based
               on the digitized area of rice plots inside the mesh are used for the analysis.

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