Understanding Statistics in the Behavioral Sciences



A graduate student in developmental
psychology believes there may be a relationship between birth weight and
subsequent IQ. She randomly samples seven psychology majors at her university
and gives them an IQ test. Next she obtains the weight at birth of the seven
majors from the appropriate hospitals

(after obtaining permission from the
students, of course). The data are shown in the following table.





 


  
Birth Weight


 




Student


  
(lbs)


IQ




1


  
5.8


122




2


  
6.5


120




3


  
8.0


129




4


  
5.9


112




5


  
8.5


127




6


  
7.2


116




7


  
9.0


130




 

a. Construct a scatter plot of the
data, plotting birth weight on the axis and IQ on the axis.
Does the relationship appear to be linear?

 

b. Assume the relationship is linear
and compute the value of Pearson r.

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