6. The dataset lowbwt.dat contains information collected for a sample of 100 low birth weight infants. Measurements of systolic blood pressure are saved under the variable sbp. Values of the Apgar score recorded five minutes after birth (a measure of neonatal oxygen deprivation) are saved under the variable apgar5. a. Using Stata, estimate the correlation between sbp and Apgar score for this population, using Pearson's correlation coefficient. b. Does it appear that Apgar score tends to increase or decrease as sbp increases? c. Using Stata, test the null hypothesis of no linear relationship between 5 minute Apgar score and sbp.