Including trees with missing values in report

[bergauers]

For my project I´ve chosen to do an complete inventory using the messurements for DBH, Tree hight, Crown width, Crown to base hight etc.
Basically when configurating my project in "Data collection options" I chose to collect more meassurements about each tree, than are potentially necessary.
However, it seems that, since I´ve chosen to collect also those extra messurements, I abolutely have to enter these values for each cell. Trees for which I, for instance could not measure the Crown to base hight because of insurmountable obsticles have to be eliminated from the analysis completely. All other values would have been complete.
Why is it not possible to estimate those few missing values by linear regression, as the would have been, if I had chosen to only collect tree species and DBH?
Is there a way to work around this?

Thank you very much!

[Jason.Henning]

Thanks for your question. The crown size parameters are grouped together in i-Tree Eco because they all used exclusively to create the estimate of leaf surface area which drives many of the ecosystem service estimates in i-Tree. Our science development team decided that it made sense to require either all of those parameter or none of them because mixing some measured and modeled values in the leaf area estimates would make it challenging to determine the accuracy of those estimates. Further, allowing some of those values to be modeled for some trees and not others would mean that some trees would have more accurate estimates of leaf area and associated benefits than others but, this wouldn't always be clear to the end user. All that being said, you are welcome to model any values you like on your own, outside of i-Tree Eco. You can then enter/import these values as your measured data. You can even use the i-Tree equations if you want. They are included in Appendix 13 of our Understanding i-Tree document. Our hope is that these restrictions will help the user have the best understanding of how those values are being modeled and how that relates to the accuracy of estimates created by i-Tree Eco.
Thanks,
Jason