Chapter09 {DanielBiostatistics10th}

Chapter 9: Simple Linear Regression and Correlation

Description

Functions for Chapter 9, Simple Linear Regression and Correlation.

Usage

predict_lm(object, newx, level = 0.95, ...)

Arguments

object

lm object, with one and only one numeric predictor

newx

(optional) numeric scalar or vector, new x-value(s) for which the fitted response(s) are to be reported

level

numeric scalar, tolerance/confidence level, default .95

...

potential arguments, not in use currently

Value

Function predict_lm returns a 'predict_lm' object, for which a print method, an autolayer and an autoplot method are defined.

See Also

predict.lm

Examples

library(DanielBiostatistics10th)
library(ggplot2)

# Example 9.3.1; Page 417 (10th ed), Page 358 (11th ed) 
head(EXA_C09_S03_01)
names(EXA_C09_S03_01)[2:3] = c('Waist', 'AT')
plot(AT ~ Waist, data = EXA_C09_S03_01, xlab = 'Waist circumference (cm), X', 
     ylab = 'Deep abdominal AT area (cm2), Y', main = 'Figure 9.3.1')

# Example 9.4.1-9.4.2; Page 432-436 (10th ed), Page 372-375 (11th ed) 
summary(m931 <- lm(AT ~ Waist, data = EXA_C09_S03_01))
cor(EXA_C09_S03_01[2:3]); cor.test(~ AT + Waist, data = EXA_C09_S03_01)
confint(m931) # confidence interval of regression coefficients
anova(m931)

# (omitted) Example 9.4.3; Page 376 (11th ed) 

# Example 9.4.3; Page 440 (10th ed)
# Example 9.4.4; Page 379 (11th ed)
plot(m931, which = 1, main = 'Figure 9.4.8 (10th) or 9.4.9 (11th)')

# Section 9.5; Page 441 (10th ed), Page 380 (11th ed) 
autoplot(predict_lm(m931)) + labs(
  xlab = 'Waist circumference (cm), X', ylab = 'Deep abdominal AT area (cm2), Y', 
  title = 'Figure 9.5.1')

# Example 9.7.1; Page 447 (10th ed), Page 386 (11th ed) 
head(EXA_C09_S07_01)
summary(mod_971 <- lm(CV ~ HEIGHT, data = EXA_C09_S07_01))
autoplot(predict_lm(mod_971)) + labs(
  xlab = 'Height (cm)', ylab = 'Cv (units)', title = 'Figure 9.7.2 (10th ed); 9.7.1 (11th ed)')

# Example 9.7.2; Page 452 (10th ed), Page 390 (11th ed) 
cor(EXA_C09_S07_01); cor.test(~ CV + HEIGHT, data = EXA_C09_S07_01) # Figure 9.7.4, 9.7.5

# Page 453, When the Hypothesized rho Is a Nonzero Value
# R does not have a function to do this