topic Retrospection and Projection in QlikView

Retrospection and Projection

christian77 — Wed, 13 Oct 2010 12:09:19 GMT

Hi:

I´d like to know more about Retrospection and Projection features of graphics with trend line on them. It doesn´t seem to do much.

I´m talking about the automated feature in the axes tab, graph properties. (not a trend analysis)

If anybody knows how to use it properly, please don´t hesitate helping me.

Thanks a lot.

Retrospection and Projection

wizardo — Wed, 13 Oct 2010 13:01:08 GMT

but its is related to trend analysis. it extends the trend line according to the x axis dimension

here is what the help sais

Backcast

This function operates on trend lines. Enter into the text edit box how far back you would like to estimate the trend line. See: Chart Properties: Expressions. The backcast portion of trend lines is displayed as dotted.

Retrospection and Projection

christian77 — Wed, 13 Oct 2010 14:31:51 GMT

Well, I´ve read the help part too. It´s so tiny that it doesn´t say what value we have to introduce in each box.

I´ve just typed '6' on each one and this is what I get.

It is not drawing new predicted bars or values. It doesn´t draw values on axis, grids or anything. Neither the back line is d o t t e d.

It shoud be more than this, i think.

Ok, Thanks.

Standing by for more.

Retrospection and Projection

wizardo — Wed, 13 Oct 2010 15:31:48 GMT

well,

since it relates to the trend-line, that relates to the x-axis..

the unit is that of the field or expression thats is the value axis

so if x-axis value is a continuous type then it extends the trend line beofre and after in as much units of x value

value x-axis=days=3

the trend-line of backcast

will start 3 days prior to the lowest value of x-axis

and the forecast 3 days after to the highest value of x-axis .

it will squize in from both size to make room for the lengthier trend-line.

hope that clarifies

BTW i haven't check the behavior when adding a reference line (from the presentation tab) into the mix lol

Mansyno