Question

A small study is conducted involving 17 infants to investigate the association between gestational age at birth ( in weeks) , and birth weight ( in gram). Please respond to the following questions. ( 15 points)

(1)   What graph would you use to display the relationship between gestational age and birth weight?

(2)   Which statistical method would you use to describe nature and strength of the relationship between gestational age?

(3)   Which statistical method would you use to predict birth weight using the information of gestational age?

(4)   Please use a linear equation Y=-4000+180X, （Y represents birth weight, and X represents gestational age to predict the birth weight of a baby with a gestational age of 40 weeks.

(5)   How much higher would you expect the birth weight to be of an infant who gestated 41 weeks compared to an infant who gestated 40 weeks?

Answer 1

(1) We will use scatter plot to display the data. X - Axis: Time in weeks Y - Axis: Weight at Birth

(2) We can check the correlation co-efficient to check the strength of the relationaship btween two variables

(3) We can use regression method to predict birth weight using the information of gestational age

(4) The linear regression equation is given by Y = -4000 + 180 X

Given, X = 40

So, Y = -4000 + 180*40 = 3200

So the birth weight would be 3200 units

(5) Using the above regreesion equation we want to find out the birth weight when X = 41

Therefore, Y = -4000 +180*41 = 3380

So, the baby is expected to weigh 180 units (=3380 - 3220) more