Simple Linear Regression

Dear Daniil

Thank you for your very prompt response. I will be in Sydney, where I grew up, in early December!

Here is the tweaked code below (minus some brackets) that does the trick.Thank you so much.

This is an incredibly useful  companion measure to your Simple Linear Regression measure, and because it works with measures it will find the equivalent of FIRSTNONBLANK in a measure. However it does not work correctly in the filtered context of a YEAR slider to filter the interval of years which the Simple Linear Regression measure does .The value changes with the slider, but the results do not correctly match the estimated starting value of the Estimated measure except for the first value of the whole dataset.

Starting Temperature =
VAR Known =
    FILTER (
        SELECTCOLUMNS (
            ALLSELECTED ( 'cetdata'[YEAR] ),
            "Known[X]", 'cetdata'[YEAR],
            "Known[Y]", [Estimated]
        ),
        AND (
            NOT ( ISBLANK ( Known[X] ) ),
            NOT ( ISBLANK ( Known[Y] ) )
        )
    )
VAR First =
    TOPN ( 1, Known, Known[X], ASC )
RETURN
    MINX ( First, Known[Y] )
            NOT ( ISBLANK ( Known[Y] ) )
        )
    )
VAR First =
    TOPN ( 1, Known, Known[X], ASC )
RETURN
    MINX ( First, Known[Y] )

Now we have to fix the filter context and figure out how to find [Ending temperature] so we can subtract [Starting Temperature] and get the trend change per filtered interval.

Thanks again--great stuff. No one else had a clue what my problem was or how to solve it.

Tony