Re: [R] Time-series analysis with treatment effects - statistical approach
Mike Marchywka wrote: I discovered a way to do repetitive tasks that can be concisely specified using something called a computer. Now that's funny :) There were not controlled tests. It was a field experiment testing the effects that various pavement designs have on underlying soil moisture. Two designs incorporated a porous pavement surface course, while two others were based on standard impervious concrete pavement...the control was just bare, exposed soil. As you can see from the graph, the control responds quickly to rainfall events, but dries out quickly as well due to evaporation. The porous pavement allows for quick infiltration of precipitation, while the impervious pavement eventually allows infiltration of rainfall, but it's delayed. My objective is to be able to differentiate between the pavement treatments, such that I can state with statistical confidence that porous pavements affects underlying soil moisture differently than impervious pavements. I think this is obvious just looking at it, but I wanted to be able to back it up with stats. What I'd done previously is to average by week. But as I mentioned, I thought that an anova table with 104 rows relating to each week was a poor way of analyzing the data. But that being said, it effectively allows me to check for treatment-related differences. Thanks for the suggestions to date. Maybe the more I explain what I'm trying to achieve, the more focussed the suggestions will be. The vaguer the question, the broader the response, right? Thanks again, Justin -- View this message in context: http://r.789695.n4.nabble.com/Time-series-analysis-with-treatment-effects-statistical-approach-tp3615856p3621179.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Time-series analysis with treatment effects - statistical approach
Hi Mike, here's a sample of my data so that you get an idea what I'm working with. http://r.789695.n4.nabble.com/file/n3618615/SampleDataSet.txt SampleDataSet.txt Also, I've uploaded an image showing a sample graph of daily soil moisture by treatment. The legend shows IP, IP+, PP, PP+ which are the 4 treatments. Also, I've included precipitation to show the soil moisture response to precip. http://r.789695.n4.nabble.com/file/n3618615/MeanWaterPrecipColour2ndSeasonOnly.jpeg I have used ANOVA previously, but I don't like it for 2 reasons. The first is that I have to average away all of the interesting variation. But mainly, it becomes quite cumbersome to do a separate ANOVA for each day (700+ days) or even each week (104 weeks). Thanks for your help, -Justin -- View this message in context: http://r.789695.n4.nabble.com/Time-series-analysis-with-treatment-effects-statistical-approach-tp3615856p3618615.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] Time-series analysis with treatment effects - statistical approach
Hello all R listers, I'm struggling to select an appropriate statistical method for my data set. I have collected soil moisture measurements every hour for 2 years. There are 75 sensors taking these automated measurements, spread evenly across 4 treatments and a control. I'm not interested in being able to predict soil future soil moisture trends, but rather in knowing whether the treatment affected soil moisture response overall. In particular, it would be interesting to inspect treatment related response within defined periods. For example, a visual inspection of my data suggests that soil moisture is equivalent across treatments during wet winter months, but during the dry summer months, a treatment effect appears. Any help on this topic would be very appreciated. I've looked far and wide through academic literature for similar experimental designs, but have not had any success as yet. Cheers, Justin Dr. Justin Morgenroth New Zealand School of Forestry Christchurch, New Zealand -- View this message in context: http://r.789695.n4.nabble.com/Time-series-analysis-with-treatment-effects-statistical-approach-tp3615856p3615856.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
