Apparent weight in a lift

When a man of 'mg' is in the lift, then the floor of the lift exerts the force R on the person. If the lift is in rest position, then R=mg, i.e., there is no resultant force occurs in this matter.
When the lift to move upwards with acceleration a, then
the force applied on the lift is F=ma
ma=R-mg
R=m(g+a)
R=mg(1+a/g)
i.e., apparent weight of the person increases a/g times when the lift is to move upwards.
When the lift to mover downwards with acceleration a, then
the force applied on the lift is F=ma
ma=mg-R
R=m(g-a)
R=mg(1-a/g)
i.e., apparent weight of the person decreases a/g times when the lift is to move downwards. So we have to understand that mass of the person does not change but weight of the person changes when he moves vertically upwards and downwards.