An Examination on Recent Upturn in Japan National Institute of Population and Social Security Research Tokyo, Japan Ryuichi Kaneko April 28-30, 2010, Lisbon Joint Eurostat-UNECE Work Session on Demographic Projections

(1) To show the usefulness of population projection in analyzing past and current demographic processes. (2) To classify and clarify the period effects in terms of changes in cohort fertility schedule. (3) To see the cause of the recent fertility upturn in Japan. Is it same as Euro & US?

Term “Period Effect” came from epidemiology, specifically from APC-Analysis, denotes changes caused by period phenomena. Demographer needs another definition, because the Temp-effect is one of period effects, but is caused by cohort changes in age distribution of the event.

Tentative Definition : Period Effect is a change in fertility rate in a certain period, which does not influence the completed fertility of participating cohorts. Period effect can’t be defined in terms of causes. We usually don’t know the causes of fertility changes. Causes are for us to be identified.

Type- T lType- T d Type- T s Type- H (1)(2) (3)(4)

Period Effect of type-T is induced by three types of timing shift in cohort fertility schedule. type-Tl : location shift type-Td : dispersion shift type-Ts : shape shift Period Effect of type-H is transient and unpredictable. incorporated in cohort fertility projections can not be in population projections

Type- T lType- T d Type- T s Type- H (1)(2) (3)(4)

Hinoe-uma

Type- T lType- T d Type- T s Type- H (1)(2) (3)(4)

type-T period effect ? (recuperation?) or type-H period effect ? (boom?)

● Actual --- Model

Figure 5 Trends of Total Fertility Rate: Observed and Assumed

(1)(2)(3)(4) (1)(2)(3)(4) (1)(2)(3)(4) (1)(2)(3)(4)

Type- H Type- H’ Type-H’ is not a genuine period effect, because it changes cohort completed fertility. It rather be classified a period-cohort effect.

 The recent upturn could mainly be explained by the period effect, which would not change cohort completed fertility, and particularly the effects that temporally works and would be redeemed in other period ( the type-H period effect ).

 The upturn seems to be caused by a rebound of the short term too-low fertility in preceding period, followed by a boom among singles and under-parity families.  These are the different in causes from the upturns seen in the US and Europe with so- called "the tempo transition. “ (type-T period effect in our terminology)

 However, if boom continues for long enough to raise the levels of completed fertility (type- H‘ effect), the long term prospect should be higher than the presently assumed.  The proposed method seems work well for the past trends to detect type-H period effects. But it may not be reliable for the current trend to the extent that predicted cohort fertility may be unreliable.

 Period Effect The period effects should be classified and clarified in terms of cohort fertility schedule shift so that type of period can be sorted and separated.  Projection Techniques for Analyses Models of population projection can play a significant role in analyzing past and current demographic processes as well as forecasting its future course.

 Thank you …

Note: Comparatively outstanding values for the age groups and birth order are underlined.