Multilingual Demographic Dictionary, second unified edition, English volume

Mean number of events (MEAN number of events)

Translation
Section	English 138	Arabic 138	Czech 138	German 138	Spanish 138	French 138	Italian 138	Japanese 138	Portuguese 138	Russian 138	Chinese 138
138-1	intensity	شدة	intenzita	Intensität —Umfang —Niveau —Quantum	intensidad	intensité	intensità	発生頻度	intensidade	Интенсивность	强度
138-2	tempo —timing	توقيت الظواهر—تقويم الظواهر الزمني	časování	Timing —Tempo —Kalender	calendario —distribución en el tiempo	calendrier	cadenza	テンポ —タイミング	tempo	Календарь	速度 —时间
138-3	ultimate frequency	تكرار النهائي	konečná četnost	endgültige Häufigkeit	frecuencia final	fréquence finale	intensità finale	最終頻度	freqüência final	Предельная частота	最终频数
138-4	mean number of events	متوسط عدد الأحداث	průměrný počet událostí	durchschnittliche Anzahl von Ereignissen	número medio de hechos —número medio de sucesos —número medio de acontecimientos	nombre moyen d’événements	numero medio di eventi	平均事象数	número médio de eventos	Среднее число событий	平均经历事件次数
138-5	period measure	مؤشرات جارية	ukazatel intervalový	Periodenmaßzahl —Querschnittmaßzahl	índices de momento	indice du moment	indici del momento	期間指標	medidas de período	Показатели условных поколений	时期指标
138-6	cohort measure	مؤشرات الفوجية—مؤشرات جيلية	ukazatel kohortní	Kohortenmaßzahl —Längsschnittmaßzahl —Generationenmaßzahl	índices de cohorte —índices de generaciones	indice de cohorte —indice de génération	indici per coorte —indici per generazione	コウホート指標	medidas de coorte	Когортные показатели	队列指标
138-7	hypothetical cohort —synthetic cohort	فوج وهمي—فوج تركيبي	fiktivní kohorta	hypothetische Kohorte —synthetische Kohorte	cohorte ficticia	cohorte fictive	coorte fittizia	仮設コウホート —合成コウホート	coorte hipotética —coorte sintética	Условное поколение —Синтетическая когорта	假设队列 —综合队列

The primary objective of cohort analysis (103-4) is the study of the intensity ¹ and tempo ² or timing ² of demographic phenomena. The intensity of a phenomenon initiated by one non-renewable event (201-4) may be measured by either the ultimate frequency ³ of occurrence for the given event or by its complement. The ultimate frequency reflects the proportion of persons who would have experienced the event, in the absence of extraneous influences, during the existence of the cohort (116-2). The intensity of a phenomenon initiated by a renewable event (201-5) such as births or migratory moves, can be measured by the mean number of events ⁴ per person in the cohort, also in the absence of extraneous influences. Tempo or timing may be defined as the distribution over time within the cohort of the demographic events corresponding to the investigated phenomenon. The results of cross-sectional analysis or period analysis (103-5) are summarized by period measures ⁵ — as opposed to cohort measures ⁶ — which can be constructed in various fashions. A commonly used technique consists in attributing the observed rates pertaining to various ages or durations to a hypothetical cohort ⁷ or synthetic cohort ⁷ .

3. This ultimate frequency or its complement has received various names according to the phenomenon studied: parity progression ratio (637-7), frequency of definitive celibacy (521-1) ... It is best not to use the word proportion as part of these names, and to reserve it for observed proportions. For instance, the frequency of definitive celibacy must be kept distinct from the proportion single at a given age, as recorded in a census.
4. It is not unusual to give the same name to the observed mean number of events per person, and to the number that would have been observed in the absence of extraneous influences such as mortality. Distinct phrases should be used; for instance, the number of children ever born (637-2) can be distinguished from cumulative fertility (636-2).
5. Because cross-sectional analysis and hypothetical cohorts were used before genuine cohort analysis, the names of period indices often seem to imply that they refer to a cohort. This usage may lead to apparent contradictions. For example, parity-specific birth probabilities may exceed one for certain years when many postponed births are made up.