Wgu C207 Qum2 Task 1 Exam Prep Tested Questions And Complete Solutions

WGU C207 QUM2 TASK 1 EXAM PREP
TESTED QUESTIONS AND COMPLETE
SOLUTIONS

◉ L6: What does r close to +1 mean?
Answer: Strong positive association.


◉ L6: What does r close to -1 mean?
Answer: Strong negative association.


◉ L6: What does r close to 0 mean?
Answer: Weak or no linear association.


◉ L6: R code for correlation
Answer: cor(x, y, use = "complete.obs")


◉ L6: R code for correlation test
Answer: cor.test(x, y)


◉ L6: R code for Spearman correlation test
Answer: cor.test(x, y, method = "spearman")

,◉ T6: R code loading thuesen dataset
Answer: library(ISwR); data(thuesen)


◉ T6: R code scatterplot for regression example
Answer: plot(thuesen$blood.glucose, thuesen$short.velocity)


◉ T6: R code regression model thuesen
Answer: mymodel <- lm(short.velocity ~ blood.glucose, data =
thuesen)


◉ T6: R code regression summary
Answer: summary(mymodel)


◉ T6: R code confidence intervals for model coefficients
Answer: confint(mymodel)


◉ T6: R code residual histogram
Answer: hist(resid(mymodel))


◉ T6: R code residuals vs fitted plot
Answer: plot(fitted(mymodel), resid(mymodel))


◉ T6: R code QQ plot with line
Answer: qqnorm(resid(mymodel)); qqline(resid(mymodel))

, ◉ T6: R code create newdata for prediction
Answer: nd <- data.frame(blood.glucose = c(5, 10, 15))


◉ T6: R code predict new values
Answer: predict(mymodel, newdata = nd)


◉ T6: R code predict confidence intervals
Answer: predict(mymodel, newdata = nd, interval = "confidence")


◉ T6: R code predict prediction intervals
Answer: predict(mymodel, newdata = nd, interval = "prediction")


◉ T6: R code Pearson correlation with missing values handled
Answer: cor(thuesen$blood.glucose, thuesen$short.velocity, use =
"complete.obs")


◉ T6: R code correlation test
Answer: cor.test(thuesen$blood.glucose, thuesen$short.velocity)


◉ T6: R code Spearman correlation test
Answer: cor.test(thuesen$blood.glucose, thuesen$short.velocity,
method = "spearman")