At my parents house I stepped on the scales - it said 196! My scales at home say 189.
So you can do everything right - set the business strategy; establish the goals and measurements; record results; monitor the results and change tactics --- only to discover that the outcomes are unfavorable. So what is the problem? Are you measuring the wrong thing? Maybe not.
Instead, you find the numbers are wrong - you've been stepping on the wrong scale.
Somewhere I read that there is a surprising number of excel spreadsheets with fatal calculation errors (the % was over 20% I believe). Yet we are so conditioned to believe the numbers when we see it on a nicely formatted computer printout. My experience in programming computers and testing software has made me a perpetual skeptic. Maybe also coming from the roots of an Accounting firm, I've also learned to always re-add the columns both ways (with the appropriate accounting tick mark).
The lesson - You get what you measure - but check scale.