When Numbers Lie
Shani Nowlin
241

Good article Shani! Stats are fun to play with but people DO need to question what they are reading more often and look at what they AREN’T being told.

70% of families with 4 children have at least 3 of the same gender.
When I heard this tidbit over lunch a while ago I found it fascinating. You would think (or at least I initially did) that the larger percentage would belong to families with 2 boys and 2 girls. I was randomly thinking about it this morning when, like a lightening bolt to the brain I realized I had been a complete idiot. I shall explain.

Your answer on this is absolutely correct but there is also a 2nd explanation for this: Parents have a choice in how many children they have.

The odds of a first child being a boy/girl are, as you said, right near 50/50. The odds for that 2nd child are also 50/50.

But, parents are more likely to have a 3rd child if the first two are both boys or both girls (45%) than they are if the first two are 1 boy and 1 girl (39%).

And that is followed further in that parents that have 3 children of the same gender are more likely to have a 4th child (28%) than parents that have 3 children of mixed genders (20%).

So parents with mixed gender children are less likely to ever qualify as one of those “families with 4 children” to begin with. If the first 2 or 3 children are of mixed genders, they are much more likely to stop having children so “families with 4 children” isn’t a random even distribution to begin with.

I only mention that because it is also important to keep in mind that stats have to be kept in context too!