TRICKY DAX Calculated Column Measures

[Anonymous]

Hi Experts

Need to add the following as calcaluated column measure into my pbix file (see images below) i am trying to populate columns I, J and k into my pbix file. The formulas used in excel are shown below.

Sample file. 

link: https://www.dropbox.com/s/47fyhkj5euzw02q/Kaplan_Miers_v1.2.pbix?dl=0

[Greg_Deckler · Accepted solution]

Hey @Anonymous , I received a request regarding confidence intervals with Kaplan Meier survival curves from @Anonymous and so I was working on it and came up with the following answer:

OK, following along from this:

http://www.real-statistics.com/survival-analysis/kaplan-meier-procedure/confidence-interval-for-the-...

And if you are following my article here:

https://community.powerbi.com/t5/Community-Blog/Kaplan-Meier-Survival-Curves-with-Power-BI-Part-2/ba...

Then in your KMDeptDaysAll table, create this measure:

ci_alpha = 0.05

This is your confidence interval, in this case 95%

And then create these columns:

ci_S(t) = 
VAR __table = FILTER(ALL(KMDeptDaysAll),[Department] = EARLIER([Department]) && [Days] <= EARLIER([Days]))
RETURN
PRODUCTX(__table,[1-e_i/d_i])

ci_se_1 = 
VAR __calc = [e_i] / ([d_i] * ([d_i] - [e_i]))
RETURN
IF(ISERROR(SQRT(__calc)),BLANK(),[ci_S(t)] * SQRT(__calc))

ci_se = 
VAR __table = FILTER(ALL(KMDeptDaysAll),[Department] = EARLIER([Department]) && [Days] <= EARLIER([Days]))
VAR __sum = SUMX(__table,[ci_se_1])
RETURN
[ci_S(t)] * __sum

ci_lower = 
[ci_S(t)] ^ IF(ISERROR(EXP(NORM.S.INV([ci_alpha]/2)/IF(ISERROR(LN([ci_S(t)])),BLANK(),LN([ci_S(t)])*[ci_se]/[ci_S(t)]))),BLANK(),EXP(NORM.S.INV([ci_alpha]/2)/IF(ISERROR(LN([ci_S(t)])),BLANK(),LN([ci_S(t)])*[ci_se]/[ci_S(t)])))

ci_upper = 
[ci_S(t)] ^ IF(ISERROR(EXP(-NORM.S.INV([ci_alpha]/2)/IF(ISERROR(LN([ci_S(t)])),BLANK(),LN([ci_S(t)])*[ci_se]/[ci_S(t)]))),BLANK(),EXP(-NORM.S.INV([ci_alpha]/2)/IF(ISERROR(LN([ci_S(t)])),BLANK(),LN([ci_S(t)])*[ci_se]/[ci_S(t)])))

Can't be certain this is all 100% correct as the original article I was working from didn't have confidence intervals. Will try to do some verification work on this.

[v-xuding-msft]

Hi @Anonymous ,

In your sample, I found  there are some values like negative number and ∞. They cause that the SQRT function returns an error. You could use the function of IF to handle them firstly. 

Best Regards,

Xue Ding

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