Styjun

I've followed multiple tutorials on scenario analysis and what if analysis in power BI. these examples are quite clear to me and I somewhat understand how they work. For example this (https://community.powerbi.com/t5/Community-Blog/Scenario-Analysis-What-Ifs-Tips-amp-Techniques-For-Power-BI/ba-p/559653).

In this example they create a table that contains values for different scenarios

5%
10%
15%
20%

etc. and the user of the report can select these. But what if instead of direct values I have categorical values, such as "Low, medium, high, very high" like:

category - trend rise
low 5%
medium 10%
high 15%
very high 20%

On my other table I have:

Value - Item - trend_default
10 A 0.3
15 A 0.2
20 B 0.4
25 B 0.15
35 C 0.10
30 C 0.05

Now with a slicer I want to first select none, one or all of Items, after which I want to select which trend rise I want to apply on selected items(low, medium, high or very high). If I select only item A then Item B and C use their trend_default value in the calculation.

EDIT 2:
How would I go on about applying the same solution if my categories had hierarchies? So from my slicer I would select three things: Category1, Year and Category2.

category1 - Year - Category2 - trend rise
POSITIVE-trends 2018 low 5%
POSITIVE-trends 2018 high 5%
POSITIVE-trends 2017 low 5%
NEGATIVE-trends 2017 very high -5%
NEUTRAL-trends 2018 low 0%
POSITIVE-trends 2018 high 5%
NEUTRAL-trends 2017 low 5%
NEUTRAL-trends 2016 very high 15%

What I tried to do to implement the hierarchies is building upon the code provided:

Value + Trend = 
SUMX ( 
 'Demo Fact Table';
 'Demo Fact Table'[Value] * 
 ( 1 +
 IF ( 
 ISFILTERED ( 'Item Chooser'[Category1] ) &&
 ISFILTERED ( 'Item Chooser'[Category2] ) &&
 ISFILTERED ( 'Item Chooser'[Category3] ) &&
 CONTAINS ( 
 'Item Chooser';
 'Item Chooser'[concatenatedFields];
 'Demo Fact Table'[concatenatedFields]
 ) && 
 HASONEVALUE ( 'Scenario - Trend'[Category] );
 VALUES ( 'Scenario - Trend'[Trend Rise] );
 'Demo Fact Table'[trend_default]
 )
 )
 )

I made a concatenated field with the three categories, in one table, however in the other table I only have two fields Category2 & category3, and am not able to match them due to this. My thought was that I could concat two fields and lookup that value in the table, but that was not viable.

ORIGINAL ANSWER

You can create your disconnected table with more than one column, like your example.

Then create a measure, based on the selected value of that table. Something like:

Value + Trend Rise = 
 VAR Multiplier = 
 1 + IF ( 
 HASONEVALUE ( 'Scenario - Trend'[Category] ),
 VALUES ( 'Scenario - Trend'[Trend Rise] ),
 0
 )
 RETURN
 SUM ( 'Demo Fact Table'[Value] ) * Multiplier

See https://pwrbi.com/so_55281950/ for worked example PBIX file

UPDATE, BASED ON EDITED QUESTION:

First, create a disconnected dimension table to choose (slice) your Items:

Item Chooser = 
 SUMMARIZECOLUMNS ( 
 'Demo Fact Table'[Item]
 )

Now you can use measure:

Value + Trend = 
 SUMX ( 
 'Demo Fact Table',
 'Demo Fact Table'[Value] * 
 ( 1 +
 IF ( 
 ISFILTERED ( 'Item Chooser'[Item] ) &&
 CONTAINS ( 
 'Item Chooser',
 'Item Chooser'[Item],
 'Demo Fact Table'[Item]
 ) && 
 HASONEVALUE ( 'Scenario - Trend'[Category] ),
 VALUES ( 'Scenario - Trend'[Trend Rise] ),
 'Demo Fact Table'[trend_default]
 )
 )
 )

It should be straightforward to modify this if you wanted to return a default trend value per item, from a related item table.

Updated example file: https://pwrbi.com/so_55281950-2/