I. (7 pts) You are given the following estimated equation birthweight 3145.85+30
ID: 1129181 • Letter: I
Question
I. (7 pts) You are given the following estimated equation birthweight 3145.85+30.83nprevist -1.814age-233.96unmarried Std. Errors (67.98) (2.917) (2.133) (27.79) n=3000 R-squared 0.0758 Where the variables are described as follows birthweight = the weight of the newborn, in grams; nprevist = the number of prenatal visits during pregnancy; age the age of the newborn's mother; unmarried = 1 if the newborn's mother is unmarried, and 0 otherwise. Provide an interpretation for each partial slope estimate in this equation. (3pts) Are the explanatory variables individually significant at 5%? (3pts) Are all the explanatory variables jointly significant at 5%? (1pt) a. b. c.Explanation / Answer
a) The three explanatory variables used are nprevist, Age and unmarried. N previst says that when the number of prenatal visy=t increase by 1 unit then the weigh of newborn increase by 30.83 units (grams). Age says that if 1 unit of age increase then the weight of newborn decrease by 1.81 units (grams). And the dummay variable unmarried says that if the mother is unmarried then the weight of newborn decrease by 233.96 units and if the mothe is married then it does not have any effect on the weight of newborn.
b) T score = parameter coeffecient/ Std error
T score of nprevist = 30.83 / 2.917 = 10.5609
since the T-score is so high the p value will is obviously more than .05 then insignificant
T score of age= 1.81/ 2.133 = 0.84857
Since t score is .84957 , the p value (using the t table) is .25 which is more tha o.o5hence insignificant.
T Score of unmarried is = 233.96 / 27.79= 8.4188
P value is more than .05 hence this is also insignificant.
c) For this we shall use F test, which take the anova into consideration.
Degree of fredom in anova is N-2= 3000-2= 2998
F score= MSR/MSE
since it is really high so the p value is more than .05 so the explanatory variable jointly is insignificant.