98% of junior doctors voted in favour of strikes.
98% of junior doctors who are members of the British Medical Association (BMA) and who voted in the ballot said they would be prepared to strike. Not all junior doctors are members of the BMA, and not all members voted. Taken as a proportion of all junior doctors (including some not affected by the changes), roughly 46-52% voted to strike.
"Junior doctors row: 98% vote in favour of strikes"
BBC News, 19 November 2015
If you read it as 98% of all junior doctors voting to strike, that's incorrect, but it is correct that 98% of junior doctors who voted on the issue backed the strike.
Out of over 37,000 doctors balloted, about 28,000 voted to strike and about 600 voted against. 98% is the proportion of votes in favour of a strike among those who responded.
9,000 people who received ballot papers didn't vote (so the response rate was 76%, as media coverage mentioned). Roughly 16,000-23,000 additional junior doctors weren't balloted. About 3,000 of these are members of the BMA but weren't eligible to vote as they won't be affected by the changes. The remainder aren't BMA members. We don't know if they'll be affected by the changes.
Up to about a third of junior doctors aren't members of the BMA
Just over 37,000 junior doctors in England who were members of the BMA were balloted. The BMA told us it didn't ballot a further 3,000 or so of junior doctors in its membership because they won't be affected by the contract changes. For example, it said doctors in the army have a different contract.
The total number of junior doctors is thought to be somewhere roughly between 53,000 and 60,000. The BMA told us it's about 53,000, but the Department for Health gave us the 60,000 figure.
So there are about 13,000-20,000 more junior doctors (somewhere between one in four and one in three) who may or may not be affected by the changes, whose opinion we don't know.
Adding all these figures in (so including some not affected by the changes), somewhere between about 46% and 52% of all junior doctors voted to strike.
About 75% of those balloted voted in favour of striking
Out of that 37,000, 76% (28,305) returned a valid ballot paper and of those 98% (27,741) said they were prepared to take part in strike action. So it's not right either to say it's "98% of balloted Junior Doctors", as a Facebook graphic puts it: about 75% of all those balloted voted to strike.
That doesn't mean the rest don't support the strike, just that we don't know what their views are.