From TFA:
> The model used was a rather naive linear model: y \sim \beta_0 + \beta_1 x ^{1/2} + \beta_2 x^{1/3}
That is not a linear model. Also, note the dent at ~July 21, when it became possible again to buy phones in advance after the first "batch" had sold out.
Comments
From TFA: > The model used was a rather naive linear model: y \sim \beta_0 + \beta_1 x ^{1/2} + \beta_2 x^{1/3}
That is not a linear model. Also, note the dent at ~July 21, when it became possible again to buy phones in advance after the first "batch" had sold out.