# Gaussian process scale targets

I am currently playing around with Gaussian process regression. I discovered some confusing facts that I would like to be answered:

1. When I optimize the parameters like the length and error terms for the covariance function I get different results for scaled targets like $y \times 100$. This leads to the next thing:

2. When I use very small targets between $0$ and $0.1$ the whole process seems to perform very poor.

Can somebody explain these behaviors to me or maybe can send a link where those problems are discussed?

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