General Discussion and Whimsical Banter

LHW99

SnowMan said:

LHW99 said:

I thought in maths you normally only rounded the answer to a calculation?

You can easily lose accuracy if you round the inputs.

That's an argument for quoting the CPI index itself to 3 decimal places, but it's almost always shown to 1 decimal place. It means the 12 month CPI can't be calculated from the CPI index itself (at least the main 1 DP version) which doesn't have a good feel to it. But it is what it is.  

There's a difference between accuracy and spurious accuracy. Some might say quoting the CPI to more than 1 DP is spurious given the subjectivity in devising the methodology used to calculate it. 

 

I understand the point, but if the official version is to use the 3 d.p. CPI indices in the calculation, then rounding those before calculation is quite possibly going to give a different answer.

Hence "lies, d@mned lies and statistics" - if you don't know the parameters used for a calculation, it's unfortunately all too easy to be misled.

Rather like presenting and arguing from graphs that on't start from zero. Fine as long as you recognise the effect it makes. On the whole I can't help feeling there may be quite a degree of "spurious accuracy" occurring in official statistics over the years