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Myth: half of all marriages end in divorce
This looks like a good reason to save money on an expensive wedding. But can it be true?
The Population Statistics Unit of Statistics New Zealand records the number of marriages registered each year and tracks how many of these marriages end in divorce. Analysis of this data shows that roughly one-third of couples who married in 1970 had divorced by their jade wedding anniversary (35 years). This suggests that two-thirds of marriages end in the death of one partner.
But aren't divorce rates increasing?
Of those who married in 1980 one-third of couples had already divorced by their silver wedding anniversary (25 years). This is still well below one-half of all marriages.
The oldest marriage certified by the Guinness Book of Records is 85 years1.
This myth is well and truly busted. But where did it come from?
There are roughly 10,000 divorces and 20,000 marriages in NZ each year and 10,000/20,000 = 1/2 - so 1/2 of all marriages end in divorce - right? Wrong, the couples divorcing in a year are not those who marry in that year, but are a subset of all those who married in preceding years and have not yet divorced.
When measuring the frequency of an event in a population (eg divorces) it is important to express the number of events in the context of the population who are likely to experience that event (sometimes called the 'at risk' population). For divorces, that population is the number of estimated marriages. The method used to bust this myth, where divorces are analysed by year of marriage, is known as a "cohort" analysis.
1 BBC News, World Edition.
Provided by Statistics New Zealand, 21 November 2006.
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