# Is a model including a square root of a variable linear in the parameters? [duplicate]

Is the model $$y = \gamma_0 + \gamma_1 + \sqrt x + \varepsilon$$ linear in parameters? ( $\varepsilon$ is the error term.)

• Is this a homework problem? I'm guessing it is. If so, here's a hint. The gamma's are the parameters. – StatsStudent Jan 26 '15 at 17:39
• I think this may be written incorrectly. I believe it should be $\gamma_1\sqrt{x}$, correct? – StatsStudent Jan 26 '15 at 17:42
• @StatsStudent: Homework or not, we need to be told what the free parameters are, especially as the model is unidentifiable as it stands. – Scortchi - Reinstate Monica Jan 26 '15 at 17:42
• @StatsStudent, that is a reasonable guess. The model as stated is clearly unidentifiable. However, I just added $\TeX$, I didn't add the "$+$". – gung - Reinstate Monica Jan 26 '15 at 17:43
• In any case, the concept of "linear in the parameters" is explained here, here, here, here, here, & here. – Scortchi - Reinstate Monica Jan 26 '15 at 17:58