Good morning to all! I have a query on the area mapping to the sampling units, since you can load the file Area by Attribute into collect survey designer, but I do not know how it works or the data schema that it should contain.

I need to assign area to each plot, for saiku analysis.

Beforehand thank you very much!

(español: Buenos días a todos! Tengo una consulta sobre la asignación de área a las unidades de muestreo, ya que puede cargar el archivo Área por Atributo en collect survey designer, pero no sé cómo funciona o el esquema de datos que debe contener.

Necesito asignar área a cada parcela, para el análisis de saiku.

De antemano muchas gracias!)

asked 21 Feb '17, 14:49

francisco_lillo_r's gravatar image

francisco_li...
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accept rate: 0%


There is already an answer of this question HERE!


Completing the answer:

Basically you need to link the plot to an area so that the plot expansion factor can be calculated.

If you have an attribute in your plot that is called region (for instance), then you can tell Collect Earth how big the regions are. Then when you run Saiku, Collect Earth will calculate the expansion factor by dividing the are of the region by the number of plots that have the attribute region set to that one.

So, in case the regions in your survey are : Los Rios and Atacama you would add an areas_per_attribute.csv file to your survey (using the files feature in the main tab of the Survey Designer) with the following data:

region,area,weight
Los Rios,1838148,1
Atacama ,7564284,1

IMPORTANT : the name of the columns are very important. Both area (in hectares) and weight should be the last two columns. Then the name(header) of the first column must coincide with the name of the attribute that you want to link from the survey (in this case we would have a Text Attribute called region in the survey )

Weight

Weight is usually set to 1. But, if you had a sampling design where there are different intensities by region this can be handy as it allows to perform calculation in Saiku by weighted numbers of plots. E.g. in "Los rios" as it is a forested area you have one plot every 2000 meters, but in "Atacama" as it is a desertic area you will have one plot every 8000 meters. Thus the weight of the points in Atacama is higher than those in Los Rios. Then you will have something like this:

region,area,weight
Los Rios,1838148,1
Atacama ,7564284,16

In this case, the weight of the plots of Atacama is 16, as there are 16 times LESS plots in Atacama compared to Los Rios (if they had the same area)

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answered 21 Feb '17, 17:39

Open%20Foris's gravatar image

Open Foris ♦♦
2805612
accept rate: 7%

Thank you very much,

I understand everything, it was totaly clear and helpfull the explanation.

Always thank the openforis team for their dedication and give us this great tool!

Best regards from Chile!

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answered 21 Feb '17, 21:18

francisco_lillo_r's gravatar image

francisco_li...
216
accept rate: 0%

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question asked: 21 Feb '17, 14:49

question was seen: 1,092 times

last updated: 21 Feb '17, 21:18