Exactly what I needed ! Thanks so much.
Now I can draw my confidence interval, using the statistics normal distribution law ! like placing my upper and lower lines with the formula :
average + Z (according to Z table) * Stdev / sqrt(total number) (for the max line)
or average - Z (according to Z table) * Stdev / sqrt(total number) (for the min line)
No better solution ?
I finally could do this, thanks again for your good help !
An easier way for a 95% interval was just to display
Avg(Aggr(Sum(Sales), Category, Date)) +/- 2 * Stdev(Aggr(Sum(Sales), Category, Date))
I just remembered this 1, 2 or 3 sigmas rule ! ahah
So the same if you want a 68% interval, just substitute factor 2 by factor 1, and for a 99% interval, substitute factor 2 by factor 3, and it's done !
Works perfectly for me !
Hi there !
Another question related to this previous example, that we solved last week :
The solution allowed us to draw another graph with the average and a confidence interval, that's great.
But what if now, I would like to display this average and interval in the same graph as the one representing the sales on vertical axis, and for dimensions date and category ?
The problem is that, I have two dimensions : Dates and Category, and the formulas Sunny adviced me last week are to be set as measures. However, you can't draw a graph with several dimensions AND several measures. You can just with several dimensions and one measure, or several measures and one dimension.
What do you advice me guys ?
What i want to see is the 3 curves of evolution of the sales along the time (one per category), and on the same graph, the average, and the confidence interval as we found last week. In fact, the final aim would be to be able to see when one curve goes out of this interval and is in a "risky" situation.
Thanks in advance for your precious help
Hi Sunny !
Sorry for the delay in responding !
So, i put attached a new excel file simplified : 3 raws, one for the name, one for the date, one for the money they have.
What i want to see is on the same visualization 1) the evolution of the money for each character along the time (from day -5 till day 0 = today) and 2) the confidence interval of 95% as we did before.
The 1), I did it easily : creating two dimensions Date and Name, and one measure : Sum(Money). As you can see on "Picture_1"
The 2), thanks to what you explained previously, I do it easily on another view, creating one dimension : Date, and two measures :
Avg(Aggr(Sum(Money), Date)) + 2 * Stdev(Aggr(Sum(Money), Date))
Avg(Aggr(Sum(Money), Date)) - 2 * Stdev(Aggr(Sum(Money), Date))
My question is now, how could I display this confidence interval on my visualization 1), to be fast able to see which is out of the confidence interval at a D date ? (as drawn on Picture_2, with in red the lower limit and green the upper limit of the 95% interval). In fact, i have already several dimensions (2 in this example), and I need several measures (3 in this example), which is impossible ...
Thanks so much for your great help and availability !
EXAMPLE_table2.xlsx 9.4 K