Cross validation is actually hugely useful for predictive models. For a simple correlation like this, it’s less of a big deal. But if you are fitting a local linearly weighted regression line for instance, chopping the data up is absolutely standard operating procedure.
Cross validation is actually hugely useful for predictive models. For a simple correlation like this, it’s less of a big deal. But if you are fitting a local linearly weighted regression line for instance, chopping the data up is absolutely standard operating procedure.