Article Figures & Data
Figures
- Figure 1.
Comparison of relative standard error (RSE) versus percent of block segments sampled in analyzed cities using simple random sampling. For most cities, a 10% RSE could be reached with a sample between 2.2% and 4.6% of the block segments. However, in Parkersburg, West Virginia, a 32% block sample was needed to attain a 10% RSE.
- Figure 2.
Average and standard error of total street tree population estimate in Syracuse, New York, based on 30 random samples of varying number of block segments. Dotted line represents the actual street tree total. Dots represent each individual sample estimate. Error bars represent standard error estimate for population total from the 30 samples.
- Figure 3.
Comparison of relative standard error versus number of sample block segments between simple random sampling and random sampling with known block length (ratio estimate) in Syracuse, New York.
- Figure 4.
The reduction of relative standard error (from Figure 3) with the addition of one block segment in Syracuse, New York. Reduction in RSE varies depending upon how many block segments were previously sampled (x-axis).
Tables
City No. blocks Street trees Removals Norway maple Totalz 10% RSEy %x Avg.w SEv Totalz 10% RSEy %x Avg.w SEv Totalz 10% RSEy %x Avg.w SEv Buffalo, New York 5,954 67,593 145 2.4 11.4 13.8 3,119 578 9.7 0.5 1.3 15,823 523 8.8 2.7 6.4 Lansing, Michigan 5,381 57,902 116 2.2 10.8 11.7 0 na na 0.0 0.0 9,788 323 6.0 1.8 3.4 Livonia, Michigan 3,357 37,854 89 2.7 11.3 10.7 471 814 24.2 0.1 0.5 10,330 277 8.3 3.1 5.3 Parkersburg, West Virginia 876 1,734 279 31.8 2.0 4.0 132 515 58.8 0.2 0.5 107 638 72.8 0.1 0.6 Syracuse, New York 5,122 34,149 185 3.6 6.7 9.2 2,345 654 12.8 0.5 1.3 8,357 329 6.4 1.6 3.1 Wilmington, Delaware 2,132 12,586 98 4.6 5.9 6.0 263 770 36.1 0.1 0.4 573 654 30.7 0.3 0.8 - Table 2.
Comparison of sample sizes needed to attain various relative standard errors (RSE) for analyzed U.S. cities.
RSE Buffalo, New York Lansing, Michigan Livonia, Michigan Parkersburg, West Virginia Syracuse, New York Wilmington, Delaware % No. % No. % No. % No. % No. % No. 20% 0.6 37 0.6 30 0.7 23 10.5 92 1.2 26 0.9 48 10% 2.4 145 2.2 116 2.7 89 31.8 279 4.5 98 3.6 185 5% 9.1 539 8.0 433 9.7 327 65.1 570 16.1 343 13.0 668 1% 71.3 4,248 68.6 3,691 73.0 2,449 98.8 858 82.7 1,764 78.9 4,043 Note: % - Percent of total block segments sampled to attain RSE; No. - Number of block segments sampled to attain RSE.
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