[R] Categorical data repeated on time analysis

Marcelo Laia marcelolaia at gmail.com
Sun Jan 24 23:26:24 CET 2010


Hi,

I am trying to analyze a data set when nematodes were killed after a
drug administration.

We have counted the number of nematode died and the number of nematode
survival at three time points.

So, there are 100% died in some plot and could be found zero percent
in another. Then, the data set have a lot of zeros.

I have googled and found a lot of information. Moreover, my data isn't
adjust to a normal distribution.

I have transformed it to square root, but, due to zeros, it don't fit
to a normal.

The design is a split-plot. I divided a Petri dish in four parts and
each day we measured one of they.

Here is a sample of the data:

trat	rep	time	killed	living	percent.killed	percent.living
1	1	48	8	6	57.14	42.86
1	2	48	17	15	53.13	46.88
1	3	48	6	4	60.00	40.00
1	1	72	17	15	53.13	46.88
1	2	72	24	33	42.11	57.89
1	3	72	11	0	100.00	0.00
1	1	96	18	28	39.13	60.87
1	2	96	19	6	76.00	24.00
1	3	96	9	10	47.37	52.63
2	1	48	7	2	77.78	22.22
2	2	48	10	4	71.43	28.57
2	3	48	8	2	80.00	20.00
2	1	72	5	2	71.43	28.57
2	2	72	14	13	51.85	48.15
2	3	72	30	1	96.77	3.23
2	1	96	2	6	25.00	75.00
2	2	96	11	15	42.31	57.69
2	3	96	3	2	60.00	40.00
3	1	48	8	8	50.00	50.00
3	2	48	6	7	46.15	53.85
3	3	48	0	2	0.00	100.00
3	1	72	3	3	50.00	50.00
3	2	72	5	1	83.33	16.67
3	3	72	18	10	64.29	35.71
3	1	96	4	0	100.00	0.00
3	2	96	0	0	0.00	0.00
3	3	96	18	19	48.65	51.35

We have counted killed and living because free-living nematode
reproduce very fast, so I need to know the number of living in the
medium.

What you suggest me for analyze this on R? What transformation I could do?

There were a specific package for that?

Have you did something like this?

Thank you very much

-- 
Marcelo Luiz de Laia
Lages - SC - Brazil
Linux user number 487797



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