Observation 1. Batch brewing is often associated with bad tasting coffee.
Observation 2. Manual brewing is often associated with good tasting coffee.
In other words batch brewing correlates with bad tasting coffee, manual brewing correlates with good tasting coffee.
What is the conclusion?
Is it that batch brewing is the cause of bad tasting coffee, or that manual brewing is the cause of good tasting coffee? Both?
If batch brewing is the cause of bad tasting coffee, then all batch brewed coffee should taste bad. If there is even one exception, that suggests the hypothesis is false.
There are of course confounding variables (such as):
People who manually brew are more likely to care about the taste of the end product. [that isn’t to say that everyone who manually brews cares about the taste, or that everyone who batch brews doesn’t, just that on average one group is more likely to care than the other]
They are more likely to (among other things):
- use nicer coffee
- use appropriate brew ratios
- use appropriate grind settings
- grind fresh
- clean their equipment
It is these considerations, not the choice of manual brewing, that results in the odds of me getting a tasty cup of coffee from a manual brew being higher than from batch.
In a similar way to my initial mistaken conclusion above, I could correlate skinny jeans to good tasting coffee. I might observe that if a barista or team of baristas seem to have a preference for skinny jeans I have a higher chance of getting better tasting coffee. This might correlate quite well, but should we conclude that this clothing has an effect on the taste of the beverage?
Less absurd perhaps is the presence of latte art on a cappuccino. I might observe that cappuccinos that I have received that have latte art on them tend to taste better on average than those that do not. Does latte art cause the cappuccinos to taste better? Or is it more likely that there is a confounding variable?