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.
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:
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.