Questions / Quant research, Take-home data cases
One fat row
Daily P&L in $k for a strategy is below. The last row is a booking error later reversed. What is the mean daily P&L with that row dropped?
day,pnl_k
1,1.2
2,0.8
3,-0.5
4,1
5,0.6
6,-0.4
7,0.9
8,25Answer it in the app It's free. You get hints, a second try if you miss, and a follow-up question.
Show the answer and worked solution
Answer: 0.5143 USD thousands (18/35)
- Drop the 25.0 row.
- Sum of seven rows = 3.6.
- 3.6/7 = 0.514.
Interview shortcut. Drop the bad row, divide by 7: 3.6/7.
Takeaway. One bad row can dominate a mean.
In the app this has a follow-up where one thing about the setup changes. Try the follow-up.