The coalition is failing women, the number who are overdue smear tests has soared 11% since they came to power, possibly due to the difficulty getting GP appointments.

When working with data, it’s a really good idea to make sure you’re working with as comprehensive a dataset as possible and that you’ve sense checked it before coming to any conclusions (this is probably less important if you’re a political party trying to make a point, but for data journalists let’s assume this is your starting point).

Every morning we go through the PA schedule looking for possible data stories to work on that day, looking for things where we can find local angles or more data.

One of the stories this morning was Labour’s research in the number of women who have missed smear tests, both most recently in 2012/13 and before the coalition came to power in 2009/10, based on HSCIC data.

Obviously the dates where chosen to fit with Labour’s narrative that the coalition is doing a bad job but the other thing that springs to mind is Jade Goody and the rise in women making smear test appointments as a result of the coverage of her illness and death.

The figures would fit, with much of the press coverage in the early part of 2009, boosting numbers into the next financial year.

So is the number of women missing smear tests a lot worse than it used to be or was 2009/10 just a lot better than normal?

The figures from the HSCIC go back usefully to 2007/08 and show that while the number of women overdue a smear test (by 3.5+ years for 25 to 49s and 5+ years for 50 to 64s) is 10.9% higher than in 2009/10…but it is only 1.3% higher than in 2007/08, suggesting this isn’t a steady downward trajectory.

Also number of women is a good figure for headlines but it’s not a great piece of data for comparison as the population is growing – so even if the proportion of women stayed the same, or even fell, there could be more women in total that missed appointments.

In terms of the proportion of women who are up to date, the figures show in 2012/13, 73.4% of women were up to date with their smear test, compared to 72.5% in 2007/08. So a smaller proportion of women are missing their smear tests now than in 2007/08 under Labour.

(And now I’m thinking I should have made a graph of this, as it would have explained it better).

Given all this, what’s most likely to be happening is that government policy has less impact on how likely women are to make a smear test appointment than press coverage of a celebrity cancer battle, and we’re just reverting back to the norm, with a standard level of refuseniks and the disorganised, after a few years where the importance of getting screened was a higher priority.

Simon Rogers was talking earlier about the need for transparency in data journalism, the need to publish or link to your data. This is an example of where knowing the data source means you can check the analysis (and for us, dig a little into the regional variations).