7 ms·

This is probably just a coincidence. Stock markets perform lower on Mondays: https://www.macroption.com/stock-market-performance-volatility-day-of-week-1307/ ht

This is probably just a coincidence. Stock markets perform lower on Mondays: https://www.macroption.com/stock-market-performance-volatility-day-of-week-1307/ https://www.macroption.com/stock-market-performance-volatili... Traffic is probably generally higher on Mondays, though I have only anecdotal evidence.

ajross 7y ago
Heh, a rare example of the "proof of correlation isn't proof of the absence of causation" fallacy. No reason that stock markets couldn't perform worse on Mondays because of the extra traffic pollution.
- jjeaff 7y ago
  But it's not like companies provide daily sales performance data to trade on. Markets move on speculation. They aren't actually pegged to company performance. How would lower cognitive ability make markets move lower on a daily basis? All I can think is higher pollution creating greater pessimism among traders.
  - ajross 7y ago
    Markets aren't perfectly efficient. Some trades are dumb. People with lower cognitive ability are more likely to place an order and forget to check fundamentals first, forget to check competitor data, or quiet frankly make whopper mistakes like confusing a ticker symbol. Think of the loons you see on /r/wallstreetbets and other spots. They live on a spectrum, and all of us have bad days. People with impaired cognitive ability are more likely to make dumb mistakes. That seems pretty obvious to me. The only question is whether or not the effect is large enough to measure using a coarse statistic like this, but that's a quantitative argument.
    - jjeaff 7y ago
      Yes, but for most dumb trades, there is someone on the other end making a deal. So the 'dumb' trades would have to lean more towards selling rather than buying. Perhaps pollution just makes one more pessimistic and therefore bearish.
- mc3 7y ago
  ??? Who ever said correlation => not causation.
  - throwaway2048 7y ago
    Pretty much every internet comment section for the last 2 decades.
    - mc3 7y ago
      I don't think so. `Correlation => Causation` is used all the time - this is the bread and butter of clickbait headlines and articles "new study shows that...", but `Correlation => ^Causation` requires some sophistication to state ... while being wrong at the same time. Maybe a tactic used to mislead? I haven't seen it ever used. To be clear `Correlation => ^Causation` is different to `Correlation => TRUE`. (In other words, there is nothing you can deduce from correlation alone).
cowsandmilk 7y ago
The journal article explicitly calls out day of week and controls for it...

ajross 7y ago

Heh, a rare example of the "proof of correlation isn't proof of the absence of causation" fallacy. No reason that stock markets couldn't perform worse on Mondays because of the extra traffic pollution.

jjeaff 7y ago
But it's not like companies provide daily sales performance data to trade on. Markets move on speculation. They aren't actually pegged to company performance. How would lower cognitive ability make markets move lower on a daily basis? All I can think is higher pollution creating greater pessimism among traders.
- ajross 7y ago
  Markets aren't perfectly efficient. Some trades are dumb. People with lower cognitive ability are more likely to place an order and forget to check fundamentals first, forget to check competitor data, or quiet frankly make whopper mistakes like confusing a ticker symbol. Think of the loons you see on /r/wallstreetbets and other spots. They live on a spectrum, and all of us have bad days. People with impaired cognitive ability are more likely to make dumb mistakes. That seems pretty obvious to me. The only question is whether or not the effect is large enough to measure using a coarse statistic like this, but that's a quantitative argument.
  - jjeaff 7y ago
    Yes, but for most dumb trades, there is someone on the other end making a deal. So the 'dumb' trades would have to lean more towards selling rather than buying. Perhaps pollution just makes one more pessimistic and therefore bearish.
mc3 7y ago
??? Who ever said correlation => not causation.
- throwaway2048 7y ago
  Pretty much every internet comment section for the last 2 decades.
  - mc3 7y ago
    I don't think so. `Correlation => Causation` is used all the time - this is the bread and butter of clickbait headlines and articles "new study shows that...", but `Correlation => ^Causation` requires some sophistication to state ... while being wrong at the same time. Maybe a tactic used to mislead? I haven't seen it ever used. To be clear `Correlation => ^Causation` is different to `Correlation => TRUE`. (In other words, there is nothing you can deduce from correlation alone).

cowsandmilk 7y ago

The journal article explicitly calls out day of week and controls for it...