Spend enough time discussing content marketing with marketers and those three little letters R-O-I will come up a lot!
It's very difficult to measure the impact of a content strategy but the article I have referenced suggests a very sensible approach, (admittedly the words "extrapolation" and "formula" come up but it's a useful exercise) in short you look at what you would have paid to get the same impact.
You can apply a similar principle to the content you share on LinkedIn:
Count the total shares of your content and multiply by the average number of LinkedIn connections to work out your potential reach.
Work out what you would pay for that many impressions via advertising or promoted content and you have a rough idea of the worth of your content.
Here’s how you can do this analysis yourself using Google Analytics and Excel: Looking only at the organic traffic for a group of content assets, find the number of entrances to the posts over the measurement period. Use Google AdWords Keyword Planner tool to find the cost per click (CPC) for the primary keyword or phrase used in each piece of content. Multiply your organic entrances by the CPC for that primary keyword and repeat across all the content. Extrapolate the data using a linear extrapolation formula in Excel. (Organic traffic typically follows a shallow bell curve that a linear extrapolation evens out.)