Thematic Accuracy Assessment Procedures. Version 2 - USGS

2.5.2 Number of Observations per Map Class.................................................................. 26
2.6 Geographic Information Systems Design Considerations............................................... 28
3.0 Field Methods (Response Design).......................................................................................... 29
3.1 Considerations that Affect the Selection of a Source of Higher Accuracy ..................... 29
3.2 Field Methodology........................................................................................................... 33
3.2.1 Field Observer Skill Level Considerations.............................................................. 33
3.2.2 Safety and Efficiency................................................................................................ 35
3.2.3 Basic Navigation ...................................................................................................... 36
3.2.4 Field Navigation Supplements and Retaining Independence from Mapping .......... 37
3.2.5 Determination of Vegetation Type in the Field........................................................ 37
3.2.6 Moving or Reshaping Observation Area ................................................................. 38
3.2.7 Recording Field Position (GPS methods)................................................................ 40
3.2.8 Reporting Field Data ............................................................................................... 41
3.2.9 Missed Sites.............................................................................................................. 41
4.0 Data Analysis.......................................................................................................................... 43
4.1 Accuracy Assessment Data.............................................................................................. 44
4.2 The Sample Contingency Table....................................................................................... 44
4.3 The Population Contingency Table ................................................................................. 46
4.4 Definitions of Measures of Overall Accuracy................................................................. 47
4.5 Users’ and Producers’ Accuracies Measures for Individual Map Classes ...................... 47
4.6 Computations of Accuracy Measures under Stratified Random Sampling ..................... 48
4.6.1 Computation of Measures of Users’ Accuracies .................................................... 48
4.6.2 Computation of Measures of Producers’ Accuracies ............................................. 49
4.6.3 Computation of Measures of Overall Accuracy...................................................... 51
4.7 Lumped Classes ............................................................................................................... 52
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