In a field where hundreds of predictions are made every day -- what stock will change tomorrow, what company CEO will announce this or that -- shockingly little value is placed on how many turn out to be right or wrong. In other words, the "batting average," so to speak, of the people making the prognostications.

In this clip from Rule Breaker Investing, Motley Fool co-founder David Gardner explains the importance of keeping track of your own investments so that you can learn from, and improve, future choices.

A transcript follows the video.

This podcast was recorded on Oct. 28, 2015. 

David Gardner: No. 6: Keep score. Keep score. Wall Street doesn't. Keep score. The media won't. Keep score, because scoring is the best way to know, A, how you're doing, and B, to get better. It's amazing to me how little scoring is going on when it comes to the world of investing. We have pundits constantly calling what the Dow Jones Industrial Average is going to be by next fall; we have individual predictions being made on stocks all the time on CNBC and many different media venues. And if they were all really good, they'd be reminding you of what was said the last time that person came on air. They'd be crediting somebody with a correct prediction, or discrediting and not having on people who consistently make bad predictions. 

There is very little scoring going on. Part of it is because the best medium of all, the Internet, is the only one that really scores. The Internet has a memory. Television has very little memory. Print tends not to have too much memory these days. If you really want to get good at something, you need to be scoring yourself. You create a learning system where you observe, "Did I do well or not?" And once you know that, you can then go on to say, "What do I need to do differently to do better?" And that system is not in place when we look at what's happening with market commentary globally across many different media channels and venues.

If you're a baseball fan, you know that it's World Series week. It's remarkable to me that we have statistics for every minor baseball player at any level -- in night games, maybe on AstroTurf, for away games. We know that. For the lowest level of minor-league baseball. But for most of the biggest names in the investment world, we have no idea what their record is. We don't know their batting average. What an incredible contrast between the world of sports, which I love and has so much scoring and so much learning, and the world of finance, which I don't love as much, and part of that is because nobody's really scoring things. 

So keep score. It's not hard to do. See how much money was there on Jan. 1 in your investment portfolio, and then on Dec. 31, see how much is there then, and calculate the percentage change. Do the exact same thing for the S&P 500. That's going to give you the stock market's return. Check yourself and see if you're beating the market. Did you beat the market last year? How are you doing this year? Simple questions. 

We have other ways of keeping score at The Motley Fool. We have Motley Fool CAPS, where you can come in and score yourself for your predictions. "I like the stock to outperform the market, thumbs up." You can even give a time frame -- next three years or next three months, your call. Or, "I don't like this stock." We score everything. We try to score as much stuff at The Motley Fool as we can, because we want to learn, because that's how we get better.