One of the interesting things about this particular analyst, IDC, is that they don't allow the empirical evidence to sway them, which is more the work of a cult than a team which is supposed to give people advice on investment.
Look at their 2010 report. Absolutely everything is wrong. Their "model" over emphasises, every time, Blackberry, Nokia and Windows phones. And underestimates iOS and Android. With the collapse of Symbian - even the CEO of Nokia didn't believe this report - they moved on to amalgamating their predictions for Symbian and Windows into one percentage. When their model fails - and I cant think of a bigger failure than that prediction for Symbian in 2014, they never apologise, and use the same model again.
A year or two before the 2010 prediction they showed iOS at 5% by now - just about where it was. In all these years Apple has pretty much beaten, or kept up with a rapidly growing market. Even when Android was at full tilt. So Apple clearly grown from 10% of the smart phone market in 2010 to 20% now, and it continuing to outpace the market. IDCs prediction of y-o-y growth for iOS is way off. So whats the story now? In the latest report they see apple growing at 10% y-o-y, while Android falls to 9.5%. While Android is slowing, Apple is about 80% y-o-y as it always has been. Both are way off. The empirical evidence that they were wrong on iOS growth before - and Android too - has no effect on their model. They plug in the same, or higher growth rates, to Blackberry and Windows to get to their previously decided upon figure, which in windows phone's case is always ahead of iOS, and always 4 years down the line.
The reports even do this from report to report. Last years report saw windows overtaking iOS in 2015, and saw it having 86% CAGR (yoy) while Apple would drop to 10%. The opposite happened last year, Windows in total has stalled, so they predicted the same again this year. From now Windows will grow at 86%, while Apple drops to 10%. Next year, it will be 2017.
Can people sue em?