Hello,
I wish to study trends in age over time in 3 large samples (>1000 individuals each) from the same population and get p for linear trend.
Samples are independent and data are available for 4 time periods separated by equal time-intervals.
Would the following be correct? Any other suggestion?
proc glm;
class (time period);
model AGE=(time period);
contrast 'linear' (time period) -3 -1 1 3;
run;
Thanks!
@EMB wrote:
Hello,
I wish to study trends in age over time in 3 large samples (>1000 individuals each) from the same population and get p for linear trend.
Samples are independent and data are available for 4 time periods separated by equal time-intervals.
Would the following be correct? Any other suggestion?
proc glm;
class (time period);
model AGE=(time period);
contrast 'linear' (time period) -3 -1 1 3;
run;
There are a few things you haven't told us, such as:
The study includes incident cases of a specific disease, and data are collected at defined periods, each period includes different participants. As part of the descriptive analysis I would like to look at trends over time in age of the diagnosed individuals.
@EMB wrote:
As part of the descriptive analysis I would like to look at trends over time in age of the diagnosed individuals.
I am totally not understanding this part.
Trends of what? Your sentence (and code) implies you want to find the trend over time of AGE. That cannot be right. Your age increases 1 year for every 1 year of change in time. No statistics or regression or p-values needed.
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