In: Statistics and Probability
A researcher is testing the hypothesis that baby weight (in pounds) at 6 months after birth is related to breastfeeding (in oz). The regression equation is Weight = 6.5 + .48 * Milk/day. The Standard Error (SE) of the slope is 0.13, and the data were gathered from a sample of 320 babies (Alpha level is set at 0.05.) Which one of the following statements is INCORRECT?
Hypothesis testing for a significant slope shows evidence that Milk/day is a statistically significant slope.
Based on this regression equation, milk intake per day positively predicts weight at 6 months.
Hypothesis testing evidence does not support the decision of rejecting the null hypothesis.
The estimated weight of a baby who has 29 oz milk per day is 20.42 pounds.
The regression equation is Weight = 6.5 + .48 * Milk/day.
We want to test the hypothesis that the hypothesis that baby weight (in pounds) at 6 months after birth is related to breastfeeding (in oz).
Standard Error (SE) of the slope is 0.13
The hypothesis testing problem is:
Vs
The test statistic is:
Since the sample size n=320 the degrees of freedom is 319
The critical t value at 5% level of significance with 319 degrees of freedom is:
tcrit=1.967
Since 3.69>1.967, we reject the null hypothesis at 5% level of significance.
Therefore hypothesis testing for a significant slope shows evidence that Milk/day is a statistically significant slope.
Hence, the statement Based on this regression equation, milk intake per day positively predicts weight at 6 months is incorrect.
The estimated weight of a baby who has 29 oz milk per day is given by:
Weight = 6.5 + .48 * 29
Weight = 6.5 + 13.92
Weight = 20.42
Therefore the estimated weight of a baby who has 29 oz milk per day is 20.42 pounds.