Tips at a coffee shop

Since I’ve graduated, I’ve worked at coffeeshops part-time. I’ve worked at this one for about two years now. I keep track of my tips.

Tips per Hour by Shift

Figure 1. Tips per hour (95% CI) by shift: Open (5:30-10:00 AM), Mid (10:00-4:00 PM), Close (4:00-10:30 PM). Open/Mid and Mid/Close are double shifts.

If you’re interested in about how big some of those differences are:

Effect Sizes for Tips by Shift Comp

What is Hedge’s g?

It’s a computation of the difference in some measure (Tips per Hour in this case) between conditions (Shift in this case) in terms of standard deviation (basically, average deviation from the mean). Basically, a Hedge’s g of 1 is equal to a difference in Tips per Hour by 1 whole standard deviation. In social science research, 0.7 (large effect) means, roughly, “You can fucking see the difference out in the world without a t-test.” Since differences in tips between the closing shift and both the opening and midday shifts are well above a g of 1, you’d expect to see clear differences (over $1.70, the standard deviation) in the tip jars between these shifts.

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2 thoughts on “Tips at a coffee shop

  1. You can quantify your willingness to take others’ shifts! I’d be really curious what the effect of tipping is per customer- in other words, what are the numbers after controlling for amount of customers? Of course this doesn’t benefit the pragmatic part of your question, as I’m sure it’s also more beneficial to have a busy shift (time flies when you’re pulling shots).

    1. If I controlled for customer volume, the effect would disappear. Predicting tips/hour by customer volume would be its own interesting correlation. We can’t pragmatically record customer volume, but we have transaction data. Manager lady just records the big numbers and throws the tapes in a cardboard box, haha.

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