There is no need to use statistics to derive class status. Class status is derived from a cursory look at the dwelling/car that one possesses.
If u live in a 3 room
HDB flat and below, you are definitely lower class.
If u live in a 4 room
HDB flat with no car, you are in between lower and middle class.
If u live in a 4-5 room
HDB flat with a car, you qualify as middle class.
If u live in a 2 room and above condo/private apartment without a car, you also qualify as middle class.
If u live in a 2 room and above condo/private apartment with a working class car, you can edge up to the top middle class.
If u live in a condo with a luxury car priced at a minimum of $200k, many will perceive you to be in the upper class.
Anything above belongs to the upper class in Singapore.