Oh, dear, my mistake. I used the old term… venerial disease. The correct term is Sexually Transmitted Disease (STD) and apparently the awareness ribbon is green.  This made me think what is the rate of the most common STD: chlamydia. As the paper will indicate, this is associated with Pelvic Inflammatory DIsease and ectopic pregnancy. The scary thing is the rate in NZ is now 3.5 per 1000 on routine screening.

Now that was from routine sampling. The rate in a survey of NZ university students was 2.7%. This shows the type of problem we have: the manner in which you measure something affects your results. Consider this paper. The authors quite correctly separated the methods by which they had data into three — number of cases reported from STD clinics, number of cases from family planning, and testing all samples. Let’s look at the first two types of data.

You can see that the results are quite different. This is because there is no denominator — we do not know how many people turn up to wht used to be called venerial disease clinics (and where there is stigma) compared with family planning (where the stigma is none).

The take home message is to treat all official datasets with a modicum of suspicion, and read the papers, not the press release.