Re: [ECOLOG-L] G-test with zero values

2014-02-13 Thread Matt V. Talluto
Jason, I’m going to have to heartily agree here. My first thought, when you ask how to “analyze” your data, is that this is a fairly broad term, and the answer will depend entirely on what your question is. I would encourage you to think in terms of parameter estimations. At the end, you will h

Re: [ECOLOG-L] G-test with zero values

2014-02-12 Thread Malcolm McCallum
Technically the definition of the nat log of zero is actually an asymptote. What does zero mean in your data? That is the key issue you must approach before modifying the information. If zero means "too small to measure but not likely zero," then you can do some decimal estimation or I think you

Re: [ECOLOG-L] G-test with zero values

2014-02-12 Thread David Schneider
Hello Jason, The 21st century approach to percent and count data is to write the model, not search for the 'right test.' In my experience it is possible for 4th year undergrads and 1st year grad students, with little stats experience, to learn this approach. Statistical analysis based on writing

Re: [ECOLOG-L] G-test with zero values

2014-02-12 Thread Gary Grossman
JasonI don't know how it works with a g-test, but the common statistical remedy for this is to add 1 or 0.1 to all numbers which then allows the calculation of a log transform but preserves the relative relationships among data points. cheers, cheers, g2 On Wed, Feb 12, 2014 at 9:56 AM, Gary Gros

[ECOLOG-L] G-test with zero values

2014-02-12 Thread Jason Hernandez
Some time ago, I inquired about ways to analyze percent cover data, and one of the suggestions was to test for heterogeneity.  The snag, however, is that this requires multiplying each cell value by its natural log.  My data set has a lot of zero values, which are important to keep; but of cours