You mean binned data? Well, you should avoid binning in the first place; better to record the failure times directly and do a maximum likelihood fit to them. But if the data is given to you like this, obviously you can't un-bin. You can do a chi-squared fit to the counts in each bin, adjusting the Weibull parameters to minimize the chi-squared. You can use these bin counts directly and fit to the CDF, or you can convert to binned failure times (4, 10-4=6, 15-10=5, etc.) and fit to the PDF.
set talkstats end=last;
if (last) then do;
*un-comment the code below, if your data past 180 minutes are indeed censored;
/* time_begin=.; cumpct=100; output;*/
data talkstats3(drop=beginpct intervalpct temp);
if _N_=1 then beginpct=0;
temp=intervalpct * &SAMPLESIZE/100;
do while (temp>0);
proc lifereg data=talkstats3;
model (time_begin, time_end) = ;
*SAS also has a model statement where you can do: model r/n = ;
but since you have interval-type survival times then you cannot use that type of model, I believe;
Thanks for your reply. Answers to your questions are:
Nope I do not know the total sample size. Only 27% has failed till the time I have mentioned. Since I do not know the sample size I am forced to assume that the rest of the sample survive greater than the max time given in my data. They would then be right censored.