From

Location

Message

Date Posted

Everywhere there are growers

There have been some 6ooo more pumpkins grown, weighed and measured since Team-Pumpkin posted the Team-Pumpkin Enhanced OTT and the Team-Pumpkin Standard OTT Charts. One of the questions is how have they performed and do they need updating. Analyses of the old and new data show they have served very well in estimating the weights of pumpkins even in the extrapolated ranges. All the new pumpkin data fits so well that no update is needed.

We have posted 2 graphs to show how all the World Record Pumpkins we could find verifiable OTT for fit on the Standard Team-Pumpkin OTT Chart in comparison to the GPC Holub/Wolf OTT Chart.

http://www.bigpumpkins.com/DisplayPhoto.asp?pid=7648&gid=-65197

3/16/2017 8:00:03 PM

Central NY

Keep up the great work!

3/16/2017 8:09:07 PM

Central Illinois

Could Team pumpkin make an app

3/17/2017 9:51:00 AM

Deer Park, WI

I am exploring the details of creating an OTT app.

3/17/2017 11:45:49 AM

Willamette Valley, Oregon

1) OTT charts aren't designed to fit the heaviest pumpkins. They are designed to fit all pumpkins. So showing that the TP chart fits heavy pumpkins well, actually emphasizes the fundamental error in the TP OTT chart rather than proving anything useful about the chart fit.

2) The TP chart over-predicts the weight of pumpkins at high OTTs on average, leading to light-to-chart pumpkins in that range. That was true when the TP chart was developed has never been corrected. If the chart doesn't fit...? ;)

Here's a table with the top 10 fruit by OTT from 2016 showing % chart for the 3 charts:

OTT.....NewGPC_2017.....OldGPC_2013.....TP
496.......+11.4..............+20.7.........+2.8
484........-5.5...............+1.5........-11.2
479.......-11.2...............-4.9........-15.9
474........-3.8...............+2.8.........-8.3
470........-1.4...............+5.1.........-5.5
469........-1.1...............+4.9.........-5.1
468........-3.0...............+3.2.........-6.9
467........+0.6...............+7.0.........-3.2
465........-4.3...............+1.7.........-7.7
464.......+11.6..............+18.6.........+7.7

7 of 10 fruit are under -5% to chart on the TP chart. The TP chart is obviously incorrect in this range. The old GPC chart was running too high in this range. This was recognized and corrections were made in the 2017 GPC chart.

3/20/2017 7:20:31 PM

Willamette Valley, Oregon

3) Looking across all the data over the past years, there is a clear trend of increasing weight for a given OTT year over year (pumpkins are getting heavier by 0.5-1% per year on average). That masks some of the high OTT light-to-chart issue with the TP OTT chart by making lower OTT pumpkins appear heavier to chart (robbing Peter to pay Paul). The trend of increasing % to chart overall is accounted for correctly in the new 2017 GPC chart.

4)The new 2017 GPC chart better fits the OTT to weight data at the high OTTs and across the full range of OTTs than any other chart, correcting bias issues with the old 2013 GPC chart equation, and adjusting for the expected increase in pumpkin heaviness year over year.

Good luck in 2017!

3/20/2017 7:20:45 PM

Central Illinois

I thought they are trying to get as many pumpkins at 0% ,if you add all of these together to find how far off they are from zero you get new GPC 75.6 - OLD GPC 146 and 2013 TP 220.3

3/21/2017 9:21:23 AM

Willamette Valley, Oregon

Yes, close to 0 is good, generally an average is better than a sum for comparison, but they both work ok in this case. I'm not sure how you did the calculation, but I come up with:

2016-Top 10 by OTT
chart....Average....Sum
GPC17...-0.7......-6.7
GPC13...+6.1......+60.6
TP.......-5.3.....-53.3

And looking at past years, TP chart is light at the top end every year:

2015-top 10 by OTT
chart....Average....Sum
GPC13...+4.2......+42.1
TP.......-6.1.....-61.0 and 6/10 under -5%, 0/10 over +5%

2014-top 10 by OTT
chart....Average....Sum
GPC13...+4.1......+41.2
TP.......-6.0.....-60.5 and 6/10 under -5%, 0/10 over +5%

2013-top 10 by OTT
chart....Average....Sum
GPC13...+2.9......+29
TP.......-4.0.....-40 and 4/10 under -5%, 2/10 over +5%

3/21/2017 12:09:48 PM

Utah

so if I'm reading this correctly - if your pumpkin is a potential world record pumpkin then use the TeamPumpkin chart, otherwise you might want to use the 2017 GPC chart.

Or if your me - use the 2005 chart (that way I have a chance to have a heavy to the chart pumpkin)

3/21/2017 5:47:20 PM

Willamette Valley, Oregon

Pretty close gordon, but you'd actually have to somehow KNOW BEFOREHAND that you had a world record weight in order for that to work (and how could you?).

That just emphasizes why the grasping-at-straws approach taken by TP to "verify" their chart is silly. It's plain to see that the TP chart is demonstrably inaccurate at high OTT and has been since its introduction.

(Not saying the old 2013 GPC chart was much better recently, but that's why we have a new chart.)

3/21/2017 7:43:24 PM

Owensboro, Ky.

Bat, in response to your (and how could you)? Lot's of folks have certified in line scales, and weigh their pkns on them! Some do it several times during the growing season! They come to weighoff's knowing up-front what their pkn weighs!! Peace, Wayne
PS...where can I find this new chart?

3/22/2017 1:20:15 AM

Willamette Valley, Oregon

True, you could weigh it on a scale through the season but then you don't need the estimation chart to know the weight. In any case it's inappropriate mathematically to select a sub-population based on weight (or WR status) to assess chart accuracy, because that necessarily excludes light-to-chart pumpkins of similar OTT and thus is a highly biased sample. A fair assessment includes all pumpkins in a given OTT Range as I have done above.

3/22/2017 1:37:27 PM

Willamette Valley, Oregon

Here's a copy/paste from an old thread on the topic that still applies today...:

3/22/2017 1:41:08 PM

Willamette Valley, Oregon

I looked some more at the 2013 data. I made two graphs that should, I hope, clarify the central problems I have with using weight cut-offs.

http://www.bigpumpkins.com/displayphoto.asp?pid=7410&gid=-50353

http://www.bigpumpkins.com/displayphoto.asp?pid=7411&gid=-50353

Both graphs show all pumpkins greater than 392 inches, which was the OTT cut-off needed to encompass all 1500 lb pumpkins.

Several things to notice on the first graph (with measured weight on the horizontal-axis):

A) In order to encompass the 47 1500 lb pumpkins an OTT cut-off at 392 inches was needed. There were 131 pumpkins at or over 392 inches, so for an improper weight-based cut off, 84 pumpkins or 64%, almost 2/3rds, must be discarded! (I was even surprised by the scale of that number.) That's a big reason why the weight based assessment is such a wrong approach and the reason we see sooo many heavy pumpkins that way.

B) Within that OTT range there is a clear relationship between weight and %-to-chart. That's another reason why the weight-based approach is wrong: Weight and %-to-chart are correlated at the upper range!

In the second graph, with OTT on the horizontal axis, you can clearly see the biased inclusion and omission of data in the 1500 lb red group. Every open dot is one that should be included for the analysis to be fair and unbiased across the range of OTT where 1500lb pumpkins occurred.

Also note the lack of correlation between OTT and %-to-chart (as it should be).

Using instead a 417 OTT cut-off (approximately 1500 lbs), all open dots to the right of the cut off are points that should be included in a proper analysis. Any red-filled dots to the left of the 417 line should be excluded from a proper analysis; consistent with my explanation earlier today.

Anyway, I hope that helps clarify the problem. So as tempting as it is, please don't fall into the trap of using a weight-based cut-off to assess an OTT-based chart.

3/22/2017 1:41:13 PM

Willamette Valley, Oregon

The new gpc 2017 chart should be posted soon, after the post-big show dust settles a little and they can get it up on the website.

In the meantime, if folks want the equation here it is in excel format:

=(((14.2/(1+7.3*2^(-A2/96)))^3+(A2/51)^2.91)-8)*0.993

Where A2 is OTT_inches
and the output is lbs

3/22/2017 1:45:37 PM

Owensboro, Ky.

bat, you would need the latest & greatest chart to know your percentage heavy or light to the chart, even if you already know the weight of your pkn! Lot's of folks are looking for & paying for heavy to chart, % wise, even if they know the correct weight of their pkn. A new chart will help them make their selection of which kin to take to the weighoff & seeds more worthy of growing!!! Peace, Wayne

3/23/2017 1:27:23 AM

Willamette Valley, Oregon

Right again Wayne. Even more reason to have a chart that fairly compares pumpkins equally across OTTs.

3/23/2017 9:57:09 AM