I'm writing a non-fiction business book and will self-publish first as an ebook and then as a hardcover. What are effective techniques I can use to have it reviewed in appropriate media, such as The Economist, The Guardian, Entrepreneur, Business Insider, etc.
There is probably nothing you can do that will get publications like the Economist to review a self published book. Major outlets like this are bombarded with more book review requests than they could ever possibly publish. One of the virtues of going with a traditional publisher is that major publishers have both the reputation to get your works considered by places like the economist and the connections to get your work to the top of the pile.
The only way I can see a major publication reviewing a self published book would be if it became a phenomenon, a book that everyone was talking about, a book so important that they could not afford to ignore it. In other words, about the time that traditional publishers would be knocking on your door wanting to take over publication, the Economist would be knocking on your door wanting to review.
If you have written a book that you think is worthy of the attention of a The Economist, then it is also worthy of the attention of a major publisher, and it would be worth your while to query the publishers of similar business books to gauge their interest.
As someone else already pointed out, major publications are inundated with review requests. They set a high bar for consideration, and one of those elements is, "How interested will our publication's readers be in learning about THIS book?" Usually that criteria is met by a positive answer to: Is this person well known? Does he or she have a strong reputation in these circles; that is, is the author an authority in this topic? Is it a unique topic or totally new angle? ...and very few people qualify.
It sounds good to say, "I'll aim for the top!" and sure, go ahead and send a query. But I think you'll find far more success by looking for second- and third-tier publications that cover that specific non-fiction area. Better for a book about banking to be reviewed in a banking magazine, for instance, where the audience is more targeted.
The downside is that few publications do book reviews anymore.
Getting a book reviewed is both important and difficult. There are a number of elements to this. On the simplest level, some of these venues will have guidelines or review pages which should let you know their policy on book reviews. You'll need to look it up, and usually it's not easy to find. Another way is to look for "department" editors, starting with "books." My experience is with different types of articles but it should be basically the same. Write a query letter (usually email) to the appropriate editor if no policy was located on their website. Make it relatively brief, well-written, interesting, and relevant to the periodical's interests. Present your book in the best possible light, and introduce yourself and what makes you unique.
But first, read a copy of the publication you're interested in or check their website and see if they actually have book reviews for books such as yours, and if so, are they brief or more in-depth. Are reviews a regular feature, in which you should query them, or are they a rarity, in which case find another venue. Also read something written by the editor or google them at least to get a sense of their take on things. Then tailor your intro/ query for that person. It helps if you like their style. The converse then is more likely to be the case. The more places you query, the more likely you are to find a positive response.
Another facet of this is making yourself known via social media and a well-done author website. Writers and editors are often the same club; once you find an entrance, on Facebook or LinkedIn or elsewhere, you can eventually become a familiar name within that circle. But for now, you'll have to market your book directly to the venues that do reviews. I am basically a book reviewer among other things, but not of your genre of book. Editors are interested in new books and have an interest in being the first to discover something really good. Consider all possibilities, big name places and smaller venues as well. There's no limit on how many reviews you can have, so aim high in both quality and volume.
There are also places that help with such things for a fee, but I am not familiar with them really. I've heard of Book Baby, which helps self-publishers, and Writers' Relief, which I believe helps submissions but may do other things such as book promotion. You may search further. Try, try, try. And good luck!