#####################################
# Low Birth Weight Analysis Using R #
#####################################

lowbwt <- read.table("lowbwt.data.txt",header=TRUE)
sbp <- lowbwt[,1]
gender <- lowbwt[,2]
tox <- lowbwt[,3]
grhem <- lowbwt[,4]
gestage <- lowbwt[,5]
apgar5 <- lowbwt[,6]

mreg1.results <- lm(sbp ~ gestage + apgar5)
print(summary(mreg1.results))
print(predict(mreg1.results, list(gestage=c(31),apgar5=c(7)),
	interval="confidence", se.fit=TRUE))

mreg2.results <- lm(sbp ~ gestage + apgar5 + gender)
print(summary(mreg2.results))
print(predict(mreg2.results, list(gestage=c(31,31),apgar5=c(7,7),gender=c(0,1)),
	interval="confidence", se.fit=TRUE))




############################
# Output of above analysis #
############################

Call:
lm(formula = sbp ~ gestage + apgar5)

Residuals:
    Min      1Q  Median      3Q     Max 
-22.374  -8.180  -1.088   4.985  39.424 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)   
(Intercept)   9.8034    12.6629   0.774   0.4407   
gestage       1.1848     0.4424   2.678   0.0087 **
apgar5        0.4875     0.4613   1.057   0.2932   
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' '  1

Residual standard error: 10.99 on 97 degrees of freedom
Multiple R-squared:  0.08944,	Adjusted R-squared:  0.07066 
F-statistic: 4.764 on 2 and 97 DF,  p-value: 0.01063

$fit
       fit      lwr      upr
1 49.94562 47.07655 52.81469

$se.fit
[1] 1.445578

$df
[1] 97

$residual.scale
[1] 10.99297




Call:
lm(formula = sbp ~ gestage + apgar5 + gender)

Residuals:
    Min      1Q  Median      3Q     Max 
-21.854  -7.996  -1.046   5.092  38.737 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)   
(Intercept)   9.3235    12.7371   0.732  0.46595   
gestage       1.1853     0.4440   2.670  0.00892 **
apgar5        0.4747     0.4635   1.024  0.30840   
gender        1.2434     2.2253   0.559  0.57764   
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 11.03 on 96 degrees of freedom
Multiple R-squared:  0.09239,	Adjusted R-squared:  0.06403 
F-statistic: 3.257 on 3 and 96 DF,  p-value: 0.02494

$fit
       fit      lwr      upr
1 49.38987 45.89836 52.88137
2 50.63322 46.85702 54.40943

$se.fit
       1        2 
1.758960 1.902385 

$df
[1] 96

$residual.scale
[1] 11.03215




############################
# lowbwt.txt file contents #
############################

sbp	gender	tox	grmhem	gestage	apgar5
43	1	0	0	29	7
51	1	0	0	31	8
42	0	0	0	33	0
39	0	0	0	31	8
48	0	1	0	30	7
31	1	0	1	25	0
31	1	1	0	27	7
40	0	0	0	29	9
57	0	0	0	28	6
64	0	1	0	29	9
46	0	0	0	26	7
47	0	0	1	30	6
63	0	0	0	29	8
56	0	0	0	29	1
49	1	0	0	29	8
87	1	0	0	29	7
46	0	0	0	29	8
66	0	0	0	33	8
42	0	1	0	33	8
52	0	0	0	29	7
51	1	0	0	28	7
47	0	0	0	30	9
54	1	0	0	27	4
64	1	0	0	33	9
37	0	0	0	32	7
36	1	1	0	28	3
45	0	0	1	29	7
39	1	0	0	28	7
29	0	0	0	29	4
61	0	0	0	30	3
53	1	0	0	31	7
64	0	0	0	30	7
35	0	0	0	31	6
34	1	0	0	29	9
62	0	0	0	27	7
59	0	0	0	27	8
36	1	0	0	27	9
47	0	0	0	32	8
45	1	0	1	31	2
62	0	0	1	28	5
75	1	1	0	30	7
44	1	0	0	29	0
39	1	0	0	28	8
48	0	0	1	31	7
43	0	1	0	27	6
19	0	0	1	25	4
63	1	0	0	30	7
42	1	0	0	28	6
44	0	0	0	28	9
25	0	0	0	25	8
26	0	0	0	23	8
27	1	0	0	27	9
35	1	0	0	28	8
40	1	0	0	27	7
44	0	0	0	27	6
66	1	0	0	26	8
59	0	0	0	25	3
24	0	0	0	23	7
40	0	0	1	26	3
49	0	0	0	24	5
53	1	1	0	29	9
45	0	0	0	29	9
50	1	0	1	27	8
64	1	0	0	30	7
48	0	0	0	30	6
48	0	0	1	32	4
58	0	1	0	33	7
67	0	0	0	27	8
40	0	0	1	31	8
48	0	0	0	26	8
36	1	0	0	27	5
44	1	0	0	27	6
53	0	1	0	35	9
45	0	1	0	28	6
54	1	0	0	30	8
44	1	1	0	31	2
42	1	0	0	30	5
50	0	0	0	27	0
48	0	0	0	25	5
29	0	0	1	25	5
30	0	0	1	26	2
36	0	0	0	29	0
44	0	0	0	29	0
46	0	1	0	34	9
51	1	1	0	30	4
51	1	0	0	29	5
43	1	1	0	33	7
48	1	0	0	30	5
52	1	0	0	29	8
43	1	0	0	24	6
42	1	1	0	33	8
48	1	0	1	25	5
49	0	1	0	32	8
62	1	1	0	31	7
45	1	0	0	31	9
51	0	1	1	31	6
52	1	0	0	29	8
47	1	1	0	32	5
40	0	1	0	33	8
50	0	0	0	28	7