IS 606 PRESENTATION

MUSA T. GANIYU
MAY 21, 2016

8.2 Baby weights, Part II. Exercise 8.1 (OpenIntro Statistics, Third Edition: page 395)

Introduces a data set on birth weight of babies. Another variable we consider is parity, which is 0 if the child is the rst born, and 1 otherwise. The summary table below shows the results of a linear regression model for predicting the average birth weight of babies, measured in ounces, from parity.

  • (a) Write the equation of the regression line.
  • (b) Interpret the slope in this context, and calculate the predicted birth weight of rst borns and others.
  • © Is there a statistically signi cant relationship between the average birth weight and parity?

Solutions: A

A typical multiple linear regression equation looks like:

\( { Y }\quad =\quad { B }_{ 0 }\quad +\quad { B }_{ 1 }{ X }_{ 1 }\quad +\quad { B }_{ 2 }{ X }_{ 2 }\quad +\quad \) ………+\( \quad { B }_{ n }{ X }_{ n }\quad \) +\( \quad { e}\\ \)

The equation of regression line is therefore,

\( { BabyWeights}\quad =\quad { 120.07}\quad -\quad {1.93}*{parity}\quad \)

where the dependent variable is Baby_weight, Intercept is 120.07 , and slope or parameter is -1.93

Solutions: B

Since 0 represent a parity with first born, while 1 represent others,

therefore,

First son parity:

\( { BabyWeights}\quad =\quad { 120.07}\quad -\quad {1.93}*{0}\quad \) = 120.07

Other parity:

\( { BabyWeights}\quad =\quad { 120.07}\quad -\quad {1.93}*{1}\quad \) = 118.14

from the above estimation, we can deduce that first son parity is 1.93 ounces greater than other parity.

Solutions: C

Hypothesis:

\( H_0: \) \( \mu_1 \) = 0

\( H_a: \) Not \( H_0: \)

From the table, we found out that the T = -1.62, P-Value = 0.1052,

but \( \alpha \) is 0.05, we therefore accept \( H_0: \), and conclude that the data did not provide a strong evidence about the slope being different from 0, and the data didnt provide prove of association between the birth weight and parity.

THANK YOU FOR YOUR ATTENTION !.