water year vs calendar year.

I am using the EGRETci package to evaluate water quality trends for data in the Mississippi, Minnesota, and St. Croix Rivers. We investigate trends on a calendar year basis.  I was just looking for some clarification to make sure I am understanding the bootstrap results correctly.

Because I am investigating trends on a calendar year basis, I made sure for my eList that paStart=1 and paLong=12.  For this site the first water quality sample was 2/8/1985 and the last sample was 12/19/2014. I then wanted to see the trend for calendar year 2005 to calendar year 2014 (last 10 years).  Here are the first few lines of my bootstrap output text file:

Minnesota River at Jordan  Chloride

Calendar Year

  Bootstrap process, for change from Water Year 2005 to Water Year 2014
                   data set runs from WaterYear 1985 to Water Year 2015
  Bootstrap block length in days 200
  bootBreak is 39  confStop is 0.7


I am confused by how the program summarizes data by water year.  The program knows I want to evaluate by calendar year, but the summary still says I am looking at water year 2005 to 2014. It then says I have samples from water year 1985 to water year 2015, because I had samples after 10/1/2014.  So does the output mean I am looking at change from calendar year 2005 to 2014 but says “water year” anyways? Or did it change my request to look at water year 2005 to water year 2014 after all?  I just want to make sure my 2014 October –December samples are being used and from this summary I’m not sure they are.

I took a look at this question and I think I know what is going on.  My question to you is ask you to run look at your original WRTDS results for calendar year for the period of interest to you.  

That means you want to do this:

eList <- setPA(paStart=1, paLong=12)
tableChange(eList, yearPoints=c(2005,2014))

from that output take note of the change values for concentration in mg/L and for flux in 10^6 kg/yr.

Now use EGRETci and do this:

caseSetUp <- trendSetUp(eList)

then it will ask you for first water year, tell it 2005,  then last water year, tell it 2014.  

then it will ask for nBoot, bootBreak and blockLength,  You can give it 5 and 5 and 200.  (It won't really matter here, I just want you to be able to get the result quickly - when you really run it you will want bigger values for the first two of these).

Then. 

eBoot <- wBT(eList,caseSetUp)

when you look at the results, near the top you will have two lines that say something like this:  

WRTDS estimated concentration change is xxx  mg/L
 WRTDS estimated flux change is          yyy  10^6 kg/yr

The xxx should match the concentration change and the yyy the flux change you got in tableChange.  

I tried it with an example of my own and it worked fine.  Assuming the numbers work out for you then the interpretation is this.  This is really a trend test on change from calendar year 2005 to calendar year 2014.

The upshot is that we need to change what our automatic output says, but the computations are doing exactly what you want.  When we started designing the software we made it work just for Water Year.  Then we changed to making it more flexible, but we never went back and changed the message that prints out.

Let us know if this experiment works.

Laura: can you look at a way of changing the code to reflect what is really being tested?  We also needs to see that it works for any arbitrary choice of paStart and paLong so it might not even be a whole year.  The paLong and paStart in eList$INFO are driving the test, but the stuff we print doesn't really reflect that.  Probably need to say what the PA actually is and defines the starting and ending  of the period being evaluated.