How to calculate the price gap

[#1]

Hello all QV masters,

I tried to create a price gap dashboard between my company brand with my competiors but my expression is incorrect.

The dashboard dimension include: Date and Brands

My Expression = avg(if(brand='my company brand',_prices) - avg(if(brand<>'my company brand',_prices)

My expection is the dashboard should have the line with value = 0, it means my company brand pricing. And my competitors brand pricing should be upper or lower the line.

Attached image is my expectation.

Thanks very much for your support