My sister belongs to a farm co-op, and volunteered to help them with their carrot harvest. Her observations about their yield were interesting.
The farm had planted a quarter acre to carrots, two different varieties, in two long rows of each.
Their harvest was at least 6000# of carrots.
(She purposely estimated low, as each row produced 15, 125# sacks of carrots.)
There was also a variety 'test plot' which she didn't see the yield from, but was told it did quite well.
This is an organic farm, with no chemical fertilizers or genetically modified hybridized varieties of plants.
Bear in mind, that this farm has taken the time to test which varieties they will plant, and does crop rotation and plows under cover crops to refresh the soils potential.
Anyone hoping to supplement their food supply or add income in a SHTF event really needs to become familiar now with their planned vegetable and fruit varieties, to maximize production in the future.
Getting your hands dirty when times are good will ultimately keep you from starving when times are bad.
Yield estimation is very important. It would flat out suck to end up with 6000 lbs of carrots. Carrots taste good and all, but it would become a waste of resources to overplant a certain species. We still bang our heads against that in our garden every year. Last year we ended up with an ass ton of tomatoes, and about 10 ears of corn (had some issues with the corn crop). This year we had a ton of corn, but it came all at once, despite an allegedly staggered maturation interval, and a ton of tomatoes, but potatoes were under my wild guess of what I thought we'd get.
It definitely merits thought and consideration. Record keeping of actual vs. estimated, climate, etc. could be useful as well.
Yields also change year to year. When testing varieties, universities usually go 3 years and average them. It is amazing how different varieties can be at the top of the list one year and at the bottom another. Weather also plays a huge role as people in the drought stricken SE should know well.