The Good News About Marriage: Debunking Discouraging Myths About Marriage and Divorce, by Shaunti Feldhahn with Tally Whitehead, claims that the overall divorce rate for first marriages must be somewhere below 28%, probably in the low 20s, and that many other often-repeated statistics on marriage and divorce are very wrong.
However, the claim above seems to account only for divorces that have already happened, not those that may happen in the future to people who have not been married for very long yet.
Feldhahn's conclusions are vigorously disputed by a blogger who calls himself "Dalrock", who seems to have a lot of insight into marriage, divorce, and statistics, and to have studied them for a long time. I think I have cited his work before on this blog. Most compellingly, he cites age-cohort studies that appear to show the youngest baby boomers having already exeprienced a 45% lifetime divorce rate. He debunks her findings further in another post after re-examining some of the data she used.
The authors, Mr. "Dalrock", and myself are all dedicated amateurs whose real expertise is in other fields. I would very much like to know what actual demographers and statisticians have to say.