Understanding Society User Support

When I was reading "Understanding Society Innovation Panel Wave 2 Results from Methodological Experiments" I tried to compare the the response in the report with the data set. I have a question about the data. According to the paper, the total sample size for the experiment on interview mode is 2,100. However, I tried to run the data set and filtered out samples who are less than 16, the total sample size was 2,148. I know there were 37 allocation errors happened during interviewing, however, there were still 11 samples not shown in the table. I would like to know whether I missed to filter unqualified sample, if so, what type of sample was been removed, thanks.