Measures of generation length (cont.)

Exercises

Age-specificfertility rates in England and Wales, 1996
Age
group		 Mid
point		 ASFR Interval
length		 Interval
births
x - x+4 a 5fx Y Y * 5fx
15 - 19 17.5 0.0298 5 0.149
20 - 24 22.5 0.0775 5 0.388
25 - 29 27.5 0.1069 5 0.535
30 - 34 32.5 0.0886 5 0.443
35 - 39 37.5 0.0372 5 0.186
40 - 44 42.5 0.0072 5 0.036
45 - 49 47.5 0.0001 5 0.001
TFR 1.74
GRR = TFR / 2.05 0.85
  mean age
(age weighted sum)/sum		 28.19 μf fertility schedule
Age-specificfertility rates in England and Wales, 1996
Age
group		 Mid
point		 ASFR Interval length Interval births Life table person-years Net fertility rate
x - x+4 a 5fx Y Y * 5fx 5Lx 5Lx* 5fx
15 - 19 17.5 0.0298 5 0.149 4.9593 0.148
20 - 24 22.5 0.0775 5 0.388 4.9523 0.384
25 - 29 27.5 0.1069 5 0.535 4.9440 0.529
30 - 34 32.5 0.0886 5 0.443 4.9328 0.437
35 - 39 37.5 0.0372 5 0.186 4.9165 0.183
40 - 44 42.5 0.0072 5 0.036 4.8908 0.035
45 - 49 47.5 0.0001 5 0.001 4.8488 0.000
TFR 1.74 Net sum 1.72
GRR = TFR / 2.05 0.85 NRR 0.84
  mean age
(age weighted sum)/sum		 28.19 μf fertility schedule   28.17 μc cohort reproduction
Age-specificfertility rates in England and Wales, 1996
Age
group		 Mid
point		 ASFR Interval length Interval births Life table person-years Net fertility rate Female pop size Actual births
x - x+4 a 5fx Y Y * 5fx 5Lx 5Lx* 5fx 5Wx 5Wx* 5fx
15 - 19 17.5 0.0298 5 0.149 4.9593 0.148 1,721,208 51,292
20 - 24 22.5 0.0775 5 0.388 4.9523 0.384 1,854,932 143,757
25 - 29 27.5 0.1069 5 0.535 4.9440 0.529 2,206,912 235,919
30 - 34 32.5 0.0886 5 0.443 4.9328 0.437 2,291,016 202,984
35 - 39 37.5 0.0372 5 0.186 4.9165 0.183 2,082,611   77,473
40 - 44 42.5 0.0072 5 0.036 4.8908 0.035 1,948,745   14,031
45 - 49 47.5 0.0001 5 0.001 4.8488 0.000 2,042,261        204
TFR 1.74 Net sum 1.72 Total births 725,660
GRR = TFR / 2.05 0.85 NRR 0.84 GFR 0.051
  mean age
(age weighted sum)/sum		 28.19 μf fertility schedule   28.17 μc cohort reproduction   28.56 μb population childbearing

Interaction Exercise 1. The table shows the ASFRs for England and Wales in 1996. Can you calculate the mean age of the age-specific fertility schedule? Hint

Remember the formula is μ f = ∑ a ⋅y⋅ f 5 x ∑ y⋅ 5 f x

a is the mid-point of the age group (i.e. 17.5, 22.5, 27.5 etc) and y is the number of years in the interval

The mean age of the age-specific fertility schedule is 28.19

Please attempt the answer.

Yes, the mean age of the age-specific fertility schedule is 28.19.

Sorry, that is not correct. Please try again.

 

Interaction Exercise 2. Click here to reveal the nLx column. Now can you calculate the mean age of childbearing in a cohort? Hint

Remember the formula is μ c = ∑ a⋅ L 5 x ⋅ f 5 x ∑ L 5 x ⋅ f 5 x

The correct answer is 28.17

Please attempt the answer.

The mean age of child bearing in the cohort is 28.17.

Sorry, that is not correct. Please try again.

 

Interaction Exercise3: Which is younger, the mean age at childbearing in a cohort or the mean of the age-specific fertility schedule? Why?

Feedback

 

The mean age at childbearing in the cohort is younger than the mean age of the age-specific fertility schedule because the cohort measure takes into account mortality of women and therefore there will be fewer births to the older age groups.

 

Interaction Exercise 4: Click here to reveal the actual population size. Now can you calculate the mean age at childbearing in the population? Hint

Remember the formula is μ b = ∑ a⋅ W 5 x ⋅ f 5 x ∑ W 5 x ⋅ f 5 x

The correct answer is 28.56

Please attempt the answer.

Yes, the correct answer is 28.56

Sorry, that is not correct. Please try again.