topic Re: DATA WITH ZERO AS DATA in Statistical Procedures

DATA WITH ZERO AS DATA

aska_ujita — Thu, 02 May 2019 13:32:14 GMT

Hello there!

I have a data of residual milk of cows and in this data have a lot of zeros, meaning that the cow haven't any milk retained in the udder.

I am using PROC GLM to analyse milk production and residual milk, as recommended.

But in this specific data, the model (too high) and R square (too low) is not good at all because the number of information with zero as observed result.

I can't delete this information, aren't outliers...

How I can manege that??

Thank you!

Aska.

Re: DATA WITH ZERO AS DATA

Ksharp — Fri, 03 May 2019 14:43:34 GMT

Try to use distribution GAMMA or TWEETIE to fit model ,better use TWEETIE distribution.

Re: DATA WITH ZERO AS DATA

aska_ujita — Mon, 06 May 2019 12:23:11 GMT

Hello Ksharp, thank you for your help.

My procedure is like this, how can I fit the distribution?

PROC GLM (or should be mixed?);
CLASS treatment po dl cow;
MODEL residual= treatment po dl treatment*po treatment*dl;
lsmeans treatment//pdiff stderr lines;
lsmeans treatment*op1/pdiff stderr lines;
RUN;

I have repeated measures of each cow by day of lactation (dl)

po is the parturition order (primiparous or multiparous)

Thank you.

Aska.

Re: DATA WITH ZERO AS DATA

Ksharp — Mon, 06 May 2019 13:45:12 GMT

I am not sure.

PROC GENMOD;
CLASS treatment po dl cow;
MODEL residual= treatment po dl treatment*po treatment*dl /dist=gamma ; /*or dist=tweetie*/