Brand volume source: expansion or competitive gains

[Guy Rombouts]

Hi,

I am looking for a rather straightforward model to assess to split the sales evolution of a brand into the part they capture from market expansion, and the part they capture from competitive gains. Straightforward is important as is t denstined to be used by non-econometric experts (students)

Let’s assume for the sake of simplicity the market is made up of 3 competing brands (A, B, C), the sum of their sales is the “sales of the market” and the market sales is growing.

So I would like to assess if brand A grows, how much comes from market expansion, how much comes from competitive gain/loss in B, and how much from competitive gain/loss on C.

The data source are weekly sales figures, +/- 150 data points

Preferably without making an assumption on the share of the market expansion (eg. share of market expansion is proportional to share of market in the previous period), but if it is with such an assumption, it is ok

Thx,

Guy

[trubador]

Simultaneous equation models or VAR-type models seem appropriate, but I do not think they are straightforward especially given the fact that target audience are not familiar with the concepts. Moreover, since you already have observed data it may be difficult to consider purely theoretical models. Sharing the data would be helpful for better assessment of the situation, I believe.

[Guy Rombouts]

Hi,

below the simple file with the volumes (in liter) of differents brands.

Regards,

Guy