Geographical bias of technological transfers' effects on growth

I am studying equations of the form

growth in a country = a0 + a1*technological gap to a leader country + a2*other variables + error

The leader country varies. I've tried France, Japan, and the United States. If the data is split into different continents, we can see if there are any regional effects linking leader countries with greater growth effects in different continents.

For gaps in the number of telephones and cell lines, there is a link, and in the direction that may be expected. The biggest growth effect in Asian countries is from a gap with Japan, and in European countries from a gap with France. The effect of a gap is not significant or beneficial in the Americas or Africa.