system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If poor performing companies of the DOW30 are replaced with better performing companies, wouldn't this invalidate the Dow Jones Industrial Average as a long term economic indicator?

The DOW Jones Industrial Average consists of 30 large successful corporations.  Every now and then, one of these is replaced with better performing corporations.  **Of course their performance will look good over time if you replace the poor performers, right?**
gpt
They don't necessarily drop poor performers - for instance, AT&T is getting dropped soon for Apple, but AT&T has been doing just fine recently. The replacement is being made because the Dow is supposed to reflect the stock market as a whole, and currently, tech stocks are underrepresented. Similarly, the last change was to remove Kraft, which was about to spin off a portion of its company, making it much smaller than before - it wasn't about it being a poor performer.