To summarise the problem, I have a project in R where I need to study the correlation between a company's promotional activities and the number of its sales per month and per location.
I have this type of database:
UGA Date Nb_Sales Nb_Mails Nb_Visits Nb_Events
A 01/2018 12 3 5 8
B 02/2018 14 0 2 5
c 03/2018 10 2 4 3
With Nb_Sales: my variable to explain. It corresponds to the number of sales
And Nb_Mails, Nb_visits, Nb_Events : These are the explanatory variables. They correspond to the numbers of promotional activities
UGA is the location
For the moment, I have carried out regressions without taking time into account. However, in real life, when a promotional activity is carried out at time t, it will affect sales at time t, but also at t+1, t+2... It is therefore necessary to take into account the temporal aspect in my regressions.
Do you have any idea how to do this? And what R code I should use?
Thanks in advance