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Phytoplankton Data Analysis
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Microcystin #8

Closed mjpdenver closed 10 years ago

mjpdenver commented 10 years ago

So far, the only analyte I have encountered censored both high and low is Microcystin. A result might appear ">0.4<5.0". I can add two new fields to the processed data file such as result_high and qual2.

Therefore this result would look like

result_num qual1 result_num2 qual2 0.4 > 0.5 <

On the user's end, this would require that one always check for the existence of an upper limit, since one could work with the first two fields without knowing of the existence of a second result.

Any suggestions?

jbeaulie commented 10 years ago

That is a bit complicated, but I can't really think of a better approach.

Although I have some experience using interval censored statistics (like Helsel's NADA book/R package), I doubt we will have enough censored observations to merit this approach. We will most likely convert the censored values to a single number after the data have been compiled. For example, we may decide that all observations censored both high and low will be set equal to the average of the upper and lower limits. I want to see how many censored values we have and consult with the phycologist before making these decisions.

mjpdenver commented 10 years ago

No problem. I am not familiar with microcystin and if it were something very esoteric or unrelated to the research you are planning I would suggest carrying the additional fields.

Date: Thu, 13 Feb 2014 10:20:53 -0800 From: notifications@github.com To: Phytoplankton-Data-Analysis@noreply.github.com CC: Matt_Pocernich@hotmail.com Subject: Re: [Phytoplankton-Data-Analysis] Microcystin (#8)

That is a bit complicated, but I can't really think of a better approach.

Although I have some experience using interval censored statistics (like Helsel's NADA book/R package), I doubt we will have enough censored observations to merit this approach. We will most likely convert the censored values to a single number after the data have been compiled. For example, we may decide that all observations censored both high and low will be set equal to the average of the upper and lower limits. I want to see how many censored values we have and consult with the phycologist before making these decisions.

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jbeaulie commented 10 years ago

Microsystin is one of the most important types of Blue-Green algae in these reservoirs and will play a big role in our data analysis. We should probably carry the qualifiers into the data set and make a very clear decision on how to deal with them.

jbeaulie commented 10 years ago

Correction, microsystin is one of the toxins produced by blue-green algae of the genus Microsystis, among others.

mjpdenver commented 10 years ago

That makes some sense - since it appears with other records that are largely water quality data.

Date: Tue, 18 Feb 2014 07:34:41 -0800 From: notifications@github.com To: Phytoplankton-Data-Analysis@noreply.github.com CC: Matt_Pocernich@hotmail.com Subject: Re: [Phytoplankton-Data-Analysis] Microcystin (#8)

Correction, microsystin is one of the toxins produced by blue-green algae of the genus Microsystis, among others.

— Reply to this email directly or view it on GitHub.