Chart of the week: Population Pyramids, Vases and Wedges

Pop­u­la­tion pyra­mids show pop­u­la­tion data by gen­der and age group. They are effec­tive in show­ing changes over time. This chart of Japan demo­graph­ics through 2050 appeared in The Econ­o­mist:

Population Pyramid: Japan

This shows three pyra­mids: Male on left, right hand side females from 1950, 2005, and 2050. (2050 is pro­jec­tion based on cur­rent trends). From 1950 to 2005, the pyra­mid turned into a vase shape until 2050 when it is pro­jected to be an inverted pyra­mid or wedge. What this visu­al­izes is the aging of Japan­ese soci­ety — in a pyra­mid, the soci­ety has a large base of younger peo­ple. For the wedge, the base is inverted as the soci­ety ages, lives longer, and has lower fer­til­ity rates.

A vari­ant of the chart was pro­duced by the National Insti­tute of Pop­u­la­tion and Social Secu­rity Research that shows three dif­fer­ent pop­u­la­tion mod­els for 2050, based on dif­fer­ent fer­til­ity assumptions:

2050 Population - Japan

A time-​lapse view of the chart is here.

An inter­est­ing view of the pat­terns of pop­u­la­tion growth is in this diagram:

Patterns of Population Charts

This series of pat­terns shows pop­u­la­tion growth, sta­sis and decline.

One way I can think of improv­ing the charts is to add a hor­i­zon­tal axis to show the male/​female per­cent­ages by age band and also indi­cate aver­age num­ber of chil­dren by parental age by a color/​shading within te band.

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