OK, attached is an example with a couple different ways of displaying the forecast. It turned out to be more complicated than I showed since you don't just have two fields, but rather a field and an expression. Here's how it ended up:
I believe the equation for the trend line for a set of points (X,Y) is this:
Y = linest_m(Y,X)*X + linest_b(Y,X)
I've done that before to be able to mouse over the trend line and see the value at that point.
By R value, I think Ben means the correlation coefficient, which would be the correl() function, but it doesn't look like you needed that, though I do think it's important to show at least the correlation when making predictive models. In some cases, you may get a prediction, but there's no reason to believe it because the data is at best very loosely correlated.
Thank you for your reply. Do you have any example of that? how to use it?
I have one Bar Chart, with Month as a Dimension and Sum(Sales) as Expression. How can I use what you said to find the equation and the next value (projection)?
OK, attached is an example with a couple different ways of displaying the forecast. It turned out to be more complicated than I showed since you don't just have two fields, but rather a field and an expression. Here's how it ended up:
