Difference between revisions of "Sample design"
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*'''A stratum is defined usually based on volume and age from the stand register''' | *'''A stratum is defined usually based on volume and age from the stand register''' | ||
| − | The stratification is done in each domain separately. The stands (their productive forest land areas) of a certain domain are related to one of the several user-defined strata. In addition to total area, the number of stands and the area of the largest stand can be viewed in each stratum. The stratum-matrix should first be arranged according to current forest state (by number of classes and class width) and, if desirable, defined by other | + | The stratification is done in each domain separately. The stands (their productive forest land areas) of a certain domain are related to one of the several user-defined strata. In addition to total area, the number of stands and the area of the largest stand can be viewed in each stratum. The stratum-matrix should first be arranged according to current forest state (by number of classes and class width) and, if desirable, defined by other variables than volume and age. |
*'''When a satisfying stratification of the domain(s) has been obtained, the total number of sample stands are decided''' | *'''When a satisfying stratification of the domain(s) has been obtained, the total number of sample stands are decided''' | ||
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*'''Next, the presupposed number of plots in a sample stand is set, depending on stand characteristics (chosen by the user)''' | *'''Next, the presupposed number of plots in a sample stand is set, depending on stand characteristics (chosen by the user)''' | ||
| − | The | + | This is called the sample plot intensity-definition part. The matrix can be re-arranged as in previous parts, by selecting preferred variables and number of classes and class width. |
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''NB: The number of plots per stand is set considering costs and assumed losses (caused by bad decisions made from erratic forest descriptions), less than three is only considered stupid. A corresponding line of reasoning is held for the number of sample trees per plot, where less than 0.5 is stupid. The plots are circular, however when, e.g., acting as reference ("ground truth") to remotely sensed data with certain (quadratic) pixel size, you should adjust the plot radius hereof and define radii in meters with two decimals.'' | ''NB: The number of plots per stand is set considering costs and assumed losses (caused by bad decisions made from erratic forest descriptions), less than three is only considered stupid. A corresponding line of reasoning is held for the number of sample trees per plot, where less than 0.5 is stupid. The plots are circular, however when, e.g., acting as reference ("ground truth") to remotely sensed data with certain (quadratic) pixel size, you should adjust the plot radius hereof and define radii in meters with two decimals.'' | ||
| + | *The plot radius is set in a similar manner. Finally, some additional settings are made, necessary in the inventory (for the sample tree sampling). | ||
*'''This part is finished by actually sampling the sample stands in each stratum (done PPS where size is the stand area)''' | *'''This part is finished by actually sampling the sample stands in each stratum (done PPS where size is the stand area)''' | ||
Inspect the sampled sample stands regarding, e.g., the total number and each stands corresponding stratum. When values in corresponding columns (e.g. P1-P3, Stratum, Plots, and Radius) looks ok, you can finish and lock the sample. | Inspect the sampled sample stands regarding, e.g., the total number and each stands corresponding stratum. When values in corresponding columns (e.g. P1-P3, Stratum, Plots, and Radius) looks ok, you can finish and lock the sample. | ||