Two Types of Filters

Several years ago, my daughters gave me a t-shirt for Christmas that they knew I’d like.

And it always comes to mind when I think about this concept.

The shirt said: “There are 10 types of people in the world, those who understand binary and those who don’t.”

(I wore that shirt until it was threadbare.)

Think about all the filters/columns you could consider using in a trading strategy.

There are perhaps hundreds that you could use.

It can be completely overwhelming – where do you even start?

I’ve found that the most useful way to think about filters is to classify them in one of two buckets.

  1. Filters where the values change during the day
  2. Filters where the values don’t change during the day

Why is that important?

Go back to the backtesting puzzle I shared a few days ago.

If you use filters that don’t change during the day, you avoid the conundrum outlined in that post.

You simplify the problem of creating a profitable trading strategy dramatically.

It’s not always possible to exclusively use filters that stay constant during the day, but I always start with those because it reduces complexity.

Tomorrow I’ll share some specific examples of my favorite filters.

-Dave