lm
step
\[ \large SBP \sim mean(SBP) \]
\[ \large SBP \sim Intercept + BMI + Age \]
Note: Intercept incorporates mean SBP when BMI and Age equals to zero.
\[ \large y_{i} = \beta_0 + \epsilon_{i} \]
\[ \large y_{i} = a + \beta_1 x_{1i} + \beta_2 x_{2i} + \epsilon_{i} \]
\[ \large \hat y_{i} = \hat\beta_0 + \hat\beta_1x_{1i} + \hat\beta_2x_{2i} \]