I’m working on a social science exercise and need support to help me learn.

Overview

In this exercise you will analyze the current fertility patterns in a country of your choosing. You will use demographic data from the UN to create a graph displaying age differences in fertility, and you will use age-specific fertility rates (ASFRs) to construct the total fertility rate (TFR). Through this exercise, you will become familiar with online demographic data sources as well as the demographic patterns in a specific place. You will learn how the TFR is constructed by doing it yourself, and in so doing, you will better understand the logic behind this fundamental measure of fertility.

Prepare

Make sure you have read the material in Population: Introduction to Demography ??(page 6-7), watched this video about how the Total Fertility Rate is constructed (????????), and watched the first part of my lecture on the TFR and Hispanic fertility in the US (????????). Refresh your memory on the concept of replacement-level fertility.

Choose a country

You can choose the same country you analyzed in Exercise 1 or you can choose a new country. Somalia is off limits because that is my example.

Get your data

This time, you will go through the United Nations World Population Prospects website (????????) yourself to extract the data you need. Begin by selecting “Age-specific fertility rates (Births per 1,000 women)” under Fertility as your desired indicator. Then, type in the name of the country you wish to analyze and select it from the drop-down menu when it pops up; click next. Select ONLY the years 2015-2020; click next. Keep all the age selections (15-19 through 45-49) and click next. Keep the selection as “By Age” and click Results.

Make a table of Age-Specific Fertility Rates

From the UN Results page, you can export the data into Excel or cut and paste them into a Google Sheet like this one. (????????) Regardless of what spreadsheet software you use, make a table that looks like this:

Age group	15-19	20-24	25-29	30-34	35-39	40-44	45-49
Births per 1,000 women	100.1	262.7	372.5	241.9	165.2	82.4	44.2

What are age-specific fertility rates? Stop for a second to think about these data and what they mean. In each of the cells we see a fertility rate for an age group of childbearing-aged women in Somalia, from 15-19 to 45-49. Which age group has the highest fertility rate in this table? The answer is 25-29 year-olds. One would interpret the 25-29 fertility rate as follows: “In Somalia in 2015-2020, there were 372.5 births per 1,000 women ages 25-29.”

How is this rate constructed? First, each and every live birth during this period is counted and the age of the mother is recorded. Typically this is done via birth certificates and vital registration systems. Separately, the population of Somalian women is counted and their ages are recorded. Typically this is done in a census. Once we know the age-specific counts of births and population, we divide the count of births (to women in the age group) by the count of women in each age group. These rates are then multiplied by a constant equal to 1000 in order to tell use the number of births per 1000 women in each age group. The constant is used simply to convert a fraction into an integer in order to make the numbers easier to read and interpret.

Now make a table where the ASFRs are converted to “births per woman”

Use the numbers in the table you created to figure out how many births per woman there are in each age group. Do this by dividing the numbers in the table by 1000, or moving the decimal three places to the left. Create a new table with the ASFRs expressed per woman. My new table looks like this:

Age group	15-19	20-24	25-29	30-34	35-39	40-44	45-49
Births per woman	0.1001	0.2627	0.3725	0.2419	0.1652	0.0824	0.0442

Notice that the numbers are the same, just the decimal place moved. Now the interpretation of the rate for 25-29 year olds is: “In Somalia in 2015-2020, there were .3725 births per woman aged 25-29.” Instead of 372 births per 1000 women, it is .3725 births per woman. It is the same rate, just a different constant in the unit of measurement (per 1 versus 1000 women). (Because it is awkward to talk about fractions of a birth, the constant of 1000 (or sometimes 100) is used to convert the rate to an integer.)

Now make a graph of age-specific fertility rates

In Excel or Google Sheets, highlight the table and click on the “insert” menu and select “chart.” You can graph the rate per 1,000 women or per woman, just make sure that the y-axis label is correct. The chart that pops up should look more or less like this. You may have to change it to a line chart or adjust the title or axis labels.

Construct the Total Fertility Rate

The TFR is a very useful measure of fertility because it tells you the level of fertility in a single and very intuitive number. Although we often simply say that the TFR is the “number of births per woman,” the formal definition is more complicated that that. The TFR is actually “the number of births a woman would have if she had births across her entire childbearing life according to current age-specific fertility rates.” Notice the “would” and “if” statements here — this measure is a hypothetical measure of a lifetime of fertility for an imaginary woman reproducing according to the way that women are actually reproducing at all ages at a certain point in time. In other words, the TFR is a period measure (using data from a single point in time, such as 2015-2020) pretending to be a cohort measure (which uses data that follows a group of people, a cohort, over time). This is a very important insight! It is the reason why the TFR is called “the period TFR” or “period fertility rate” and why it is biased by tempo (or timing) changes to fertility — it captures only what is going on at a certain point in time. Remember this when reading the Parrado reading about Hispanic fertility in the US.

The way we construct the TFR is by adding up the ASFRs at every age. Because the TFR is per woman, not per 1000 women, we want to use the per-woman ASFRs. What we’re doing is calculating what would happen if a woman lived through her reproductive years and reproduced according to current age-specific fertility rates — how many births would she have at age 15, age 16, age 17, age 18… and so on through age 45? To do this, take the table of age-specific fertility rates per woman and add them up, but remember to add each one 5 times, for each year within the 5-year age groups:

Age group	15-19	20-24	25-29	30-34	35-39	40-44	45-49
Births per woman	0.1001+ 0.1001+ 0.1001+ 0.1001+ 0.1001+	0.2627 + 0.2627 + 0.2627 + 0.2627 + 0.2627 +	0.3725 + 0.3725 + 0.3725 + 0.3725 + 0.3725 +	0.2419 + 0.2419 + 0.2419 + 0.2419 + 0.2419 +	0.1652 + 0.1652 + 0.1652 + 0.1652 + 0.1652 +	0.0824 + 0.0824 + 0.0824 + 0.0824 + 0.0824 +	0.0442 + 0.0442 + 0.0442 + 0.0442 + 0.0442 +

= 6.345

Notice that the quicker way to do this is to multiply each ASFR by 5 and then sum (or vice versa). The formula is ?nASFRx * n where x is the start of the age group and n is the length of the age group. This symbol ? means sum.

The interpretation of the TFR is: In Somalia in 2015-2020, the TFR was 6.3 births per woman, which is the average completed fertility per woman, if each woman reproduced according to age-specific fertility rates from that period.

Answer these questions & turn in your work

Turn in a document with the following items:

• Your table of the ASFRs per 1000 women
• Your table of the ASFRs per woman
• Your graph of the ASFRs (can be per 1000 women or per woman)
• Your calculation of the TFR — show your work
• Answers to these questions in full sentences:
  1. Interpret the largest ASFR per 1,000 women in a sentence using appropriate units of measurement. Be sure to remind us the place & time the data come from (country and years).
  2. Interpret the largest ASFR per 1 woman in a sentence using appropriate units of measurement. Be sure to remind us the place & time the data come from (country and years).
  3. Interpret the TFR in a sentence using the more precise interpretation of the measure, i.e., mention the assumption behind statement the “births per woman.”
  4. Based on this TFR, what stage of the demographic transition is your country in, and why?
  5. Is this TFR replacement-level fertility in your country? Why or why not?

How this will be graded

We will grade for precision, accuracy, and completeness. The tables and graph are worth 1 point each and must be clear, accurate, and appropriately labeled for full credit. The calculation of the TFR is worth 2 points and will be graded for correctness; please remember to include your math so we can discern the source of any errors. Each question is worth 1 point and will be graded for accuracy and completeness. We will deduct .5 points for minor errors and omissions. We will deduct 1 point for more substantial errors or omissions.