The accompanying data on x head circumference z score a com

The accompanying data on x = head circumference z score (a comparison score with peers of the same age - a positive score suggests a larger size than for peers) at age 6 to 14 months and y = volume of cerebral grey matter (in ml) at age 2 to 5 years were read from a graph in an article.

  


(c) Predict the volume of cerebral grey matter for a child whose head circumference z score at age 12 months was 1.8. (Give the answer to two decimal places.)

Solution

a)

Using technology, like the CORREL function in Excel,
              
r =    0.741233625   [ANSWER]      

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b)

Using technology, we get              
              
slope =    32.80079564          
intercept =    712.7163478          
              
Thus, the regression line is              
              
y^ =    32.80079564x +   712.7163478 [ANSWER]

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c)
Thus, if x =    1.8  
      
Then      
      
y^ =    771.75778 [ANSWER]