Please explain this histogram

Hi

I'm using neural network matlab fitting tool

it's hard to understand error histogram with 20bins

what is bar means? the bar at error value 0.001502 is the best performance? if yes, please tell me why

and what is means zero error?

I attatched my graph. please reply ASAP.

Thank you.

Answer 1

[Inho Kim]

Hi Nayoung,

Typically errors are calculated with L1 (abs(errors)) or L2 ((errors)^2) norms. Meaning that it cancels out signs from difference between target and output. The above bar graph doesn't have neither absolute or square for errors, it has negative errors which isn't typical. Nonetherless errors are close to zero meaning the output is close to target value, the NN models well.

1. The height of bar in the Bar plot means how many data points are near the bin value.
2. 0.001502 is selected error value based on bin number setup in histogram function (i.e. histogram(data,20)), it can be changed if you use different bin value. You can try bin number with 50 or 100.
3. 0.001502 is the closest number to 0 among those bin numbers. Because error = 0 means the ourputs are close to the target, so model performance is good if the bin bars close to zero are taller than higher error numbers.

Hope this helps you.

Best,

IK

Answer 2

[nayoung park]

Thank you for reply me.

But, I don't understand well... because I'm using this tool first time.

i don't have enough basic concept..

1. You means error values don't have to minus value??
2. What is the y axis? is it the number of traning, validation and test data set?
3. why the highest bar exist? is it mean highst bar has 0.001502 error values?
4. what is zero error? I don't understand zero error line means. it means 0? it means distribution which bar close 0?

I'm sorry for many queastion.. if you are korean,you can tell me korean