Y log E rij i j k

Where i is the effect of the ith age group, j the jth period and k is the kth birth cohort where k= I-i+j expresses the identifiability problem due to the perfect linear relation between age, period and cohort Age=Period-Cohort (A=P-C).

Age Period Cohort Models: A simple explanation

M C Malvezzi PhD

Y log E rij i j k

Where i is the effect of the ith age group, j the jth period and k is the kth birth cohort where k= I-i+j expresses the identifiability problem due to the perfect linear relation between age, period and cohort Age=Period-Cohort (A=P-C).

The age effect

is expressed as

an age specific

mortality rate.

Age Period Cohort Models: A simple explanation

M C Malvezzi PhD

Y log E rij i j k

Where i is the effect of the ith age group, j the jth period and k is the kth birth cohort where k= I-i+j expresses the identifiability problem due to the perfect linear relation between age, period and cohort Age=Period-Cohort (A=P-C).

The age effect

is expressed as

an age specific

mortality rate.

The period

effect is

expressed as a

relative risk to

the reference

period

Age Period Cohort Models: A simple explanation

M C Malvezzi PhD

Y log E rij i j k

Where i is the effect of the ith age group, j the jth period and k is the kth birth cohort where k= I-i+j expresses the identifiability problem due to the perfect linear relation between age, period and cohort Age=Period-Cohort (A=P-C).

The age effect

is expressed as

an age specific

mortality rate.

The period

effect is

expressed as a

relative risk to

the reference

period.

The cohort effect is

expressed as a

relative risk to the

reference cohort.

Age Period Cohort Models: A simple explanation

M C Malvezzi PhD