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Willamette Valley, Oregon

The current GPC OTT chart (v.2017), which predicts weights from the OTT measurement, performed well again this year.

Overall, top to bottom, the chart averaged +0.4%, (less than 1% difference from estimated) which is only ~3 lbs difference for the average 850 lb pumpkins and up to 10 lbs average difference for the largest pumpkins vs actual weight .

For 500+" OTT (3 pumpkins topped this) the average percent to chart was -0.7% this year (or -16 lbs or so out of 2400+ lbs) showing that the equation is predicting the weight of the largest ott pumpkins very well.

Any individual pumpkin will vary from the predicted average. On average 2/3 of the individual fruit fall within +/-9.3 percentage points of 0% to chart.

Preemptive reminder that to assess the chart you have to sort or pick groups by OTT, not by weight.
Selecting/sorting by weight creates a biased statistical sample (it necessarily leaves out light pumpkins that are farther down the weight list) and will give misleading answers.

10/29/2022 4:30:08 PM

Grittyville, WA

It helps that the 1885.5 Werner refuses to go significantly heavy to chart. Since this is currently the dominant genetic force it should help give the chart a few more years of good predictions.

10/30/2022 3:01:53 AM

President - GPC

Explained well Scott. Thanks for keeping on top of the math....

10/31/2022 11:52:14 AM

Stanwood, Washington

A sample size of 3 seems too small to draw any conclusions. The 2017 chart requires an OTT of 461 to estimate at 2000 pounds. There were 37 Pumpkins that measured 461 or larger this year.

25 of them were heavy to the chart.

8 of them were 10% or more heavy while only one was 10% or more light.

15 of them were 5% or more heavy while only 5 were 5% or more light.

Overall, the Mean percentage to chart for Pumpkins estimating at 2000 pounds or larger was 3.35% Heavy.

The total estimated weight for these 37 pumpkins was 80,829 pounds and the actual weight was 83,526 pounds. which means that the average Pumpkin that estimated 2000 pounds ended up 73 pounds above chart.

10/31/2022 5:00:33 PM

Stanwood, Washington

Looking at 2021 data for the same sample set, There were 17 Pumpkins estimating at 2000 Pounds. 14 of them went heavy. 12 went 5% or more heavy, 1 went 5% or more light and the Average was 95 pounds above chart.

10/31/2022 5:13:39 PM

Willamette Valley, Oregon

Thanks Captain 97. >460" OTT is a range I've reported out in the past, so it's interesting to look at that range again.

Here are the average OTT chart biases over the years for the largest by OTT (460in and over, which is where it's the worst) and overall for the 2017 GPC OTT chart:

Year OTTover460" AllAG
2022 +3.35% +0.40%
2021 +4.55% -0.15%
2020 +2.09% +0.34%
2019 +3.33% +0.42%
2018 +4.31% +0.12%
2017 -2.44% -1.31%

So this year's >460" OTT pumpkins are a little better than last year at fitting the chart and staying in a range that's just a bit heavy, but not looking like it's on a strong trend to imminently get much worse.

At some point I expect we will need to refit the OTT equation, because we have seen that pumpkins historically tend to get heavier-to-chart over time, presumably because people select for that trait, but that trend has not been strong over the past few years after a huge jump in '18.

11/4/2022 12:39:44 AM

Western NY

Good breakdown.

It might not be a bad idea to plan an update after the 2023 data is in. I'm guessing a +2.5% adjustment in the 400-460 range, and a +3.5% in the 460-500 range. Not enough pumpkins in the 500+ range yet, but I don't see why the trend wouldn't continue with enough pumpkins.

11/4/2022 8:46:09 AM