Personal data & algorithms

If search engines and their advertising partners gather data about someone’s internet search history and search habits; and if they then use this information to determine whether they should be offered or refused services based on that data; or if they offer them a price for something based on that information thereby instigating price discrimination; or if they build up a picture of who they think that person is based on information they have collected, and take it much further by using the power of big data and predictive analytics to infer or predict a likelihood that  the person fits into this or that pidgeon hole:

How do you know what data they are relying on

Whether it is accurate

How do you know how that data is being used

If its new derived information derived using predictive analytics what control or rights does the individual have over it, if any

How are the companies that use this information accountable

How do we get to know how the algorithms actually work

A few weeks ago I was working from home and was undertaking a piece of research on substance abuse and drug overdoses of US veterans. What on earth would anyone make of that if they were to look at my search history. At what point would I be given an opportunity to say, oh excuse me, but please be aware that this doesn’t say anything about me, it was for work, and it should be ignored when you are coming up with your sophisticated profiling?