On the classroom level, that means teachers spend about 1 minute of their time seeing who is in the room, who is late, and inputting absences if need be. Counselors and/or secretaries analyze this data to determine necessary interventions.
In contrast, thus far I have not seen any student of my school swipe any ID in front of any reader; additionally, I have had to bubble in attendance on sheets that are to be returned to the office at a specific time where they are - I assume - digitally transferred to a database of some kind. The only reason I assume this is that on the attendance sheet I received today there was data from yesterday already bubbled in.
Also, when our academic classes begin in earnest (right now we are doing a week of orientation in our "crews" or homerooms/advisories for others to understand) we will be given bubble sheets to fill in daily and return weekly. This seems odd to me because then the data is analyzed more slowly. How does a centralized person know if a student has been absent four days in a row? It puts more burden on the teacher (especially with class sizes ballooning).
I cannot speak for all New York public schools but I am confused why there is not centralized system in use at all schools across the city. I would love to learn more about this.