b) Regression birthweight on smoker, alcohol, and nprevist. Call: lm(formula = b

Question

b) Regression birthweight on smoker, alcohol, and nprevist.

Call:
lm(formula = birthweight ~ smoker + alcohol + nprevist)

Residuals:
Min 1Q Median 3Q Max
-2733.53 -307.57 21.42 358.09 2192.70

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 3051.249 34.016 89.701 < 2e-16 ***
smoker -217.580 26.680 -8.155 5.07e-16 ***
alcohol -30.491 76.234 -0.400 0.689
nprevist 34.070 2.855 11.933 < 2e-16 ***
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 570.5 on 2996 degrees of freedom
Multiple R-squared: 0.07285,   Adjusted R-squared: 0.07192
F-statistic: 78.47 on 3 and 2996 DF, p-value: < 2.2e-16

(c) An alternative way to control for prenatal visits is to use the binary variables tripre0 through tripre3. Regress birthweight on smoker, alcohol, tripre0, tripre2, tripre3.
i. Why is tripre1 excluded from the regression? What would happen if you included it in the regression?
ii. The estimated coefficient on tripre0 is large and negative. What does this coefficient measure? Interpret its value.
iii. Interpret the value of the estimated coefficients on tripre2 and tripre3.
iv. Does the regression in (c) explain a larger fraction of the birth weight than the regression in (b)?

Call:
lm(formula = birthweight ~ smoker + alcohol + tripre0 + tripre2 +
tripre3)

Residuals:
Min 1Q Median 3Q Max
-3029.55 -307.55 31.35 372.45 2401.29

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 3454.55 12.65 273.077 < 2e-16 ***
smoker -228.85 27.16 -8.424 < 2e-16 ***
alcohol -15.10 77.54 -0.195 0.845613
tripre0 -697.97 106.88 -6.531 7.66e-11 ***
tripre2 -100.84 29.62 -3.404 0.000672 ***
tripre3 -136.96 59.58 -2.299 0.021595 *
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 578.7 on 2994 degrees of freedom
Multiple R-squared: 0.04647,   Adjusted R-squared: 0.04487
F-statistic: 29.18 on 5 and 2994 DF, p-value: < 2.2e-16

Explanation / Answer

i did not get what calculation should i do with the numbers

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