How can I find the best correlation between variables ?


I would like to investigate three element based on the dataset in appendix.

  • Is there a correlation between the contact of month N and sales of month N, N+1 (equal to N with one month shift, N+2 (equal to N with two months shift)
  • How can we know the most efficient number of contacts to maximize sales ? with constraint ? without constraint ?
  • Which delay is most relevant to consider for having an impact on the sales ?

Thanks in advance for your help.

Basket7777 ;)