R Programming Language Multiple Choice Questions on “Linear Regression ”.
1. Which of the following convert a matrix of phi coefficients to polychoric correlations?
a) poly()
b) qline()
c) phi2poly
d) multi.plot()
Answer: c
Clarification: In statistics, polychoric correlation is a technique for estimating the correlation between two theorized normally distributed continuous latent variables, from two observed ordinal variables.
2. Which of the following is used to plot multiple histograms?
a) multi.plot()
b) multi.hist
c) xyplot.multi()
d) poly()
Answer: b
Clarification: A histogram is a graphical representation of the distribution of numerical data.
3. Which of the following count the number of good cases when doing pairwise analysis?
a) count.pairwise
b) count() +
c) anova.para()
d) count.poly()
Answer: a
Clarification: Pairwise comparison generally is any process of comparing entities in pairs to judge which of each entity is preferred.
4. Which of the following gives the summary of values likes mean etc?
a) mean
b) sd
c) describe
d) lm
Answer: c
Clarification: Describe give means, sd, skew, n, and se.
5. The purpose of correct.cor is to correct _________ in values.
a) difference
b) reliability
c) error
d) similar
Answer: b
Clarification: Correlation matrix and a vector of reliabilities is given to correct reliability.
6. What plot(s) are used to view the linear regression?
a) Scatterplot
b) Box plot
c) Density plot
d) Scatterplot, Boxplot, Density plot
Answer: d
Clarification: Each plot has its own importance of highlighting a specific feature. Scatter plot is used to visualise the relationship between the variables, Box plot is used to spot the outliers which effect line of best fit.
7. Common Metrics which are used to select linear model are ____________
a)
R-Squared Lower the better
F-Statistic Higher the better
b)
R-Squared Lower the better
F-Statistic Lower the better
c)
R-Squared Higher the better
F-Statistic Higher the better
d)
R-Squared Higher the better
F-Statistic Lower the better
View Answer
Answer: c
Clarification: For choosing linear regression model it is always advised to have more R-squared and lower F-Statistic. It ensures the best fit for the given data.
8. In lm(response ~ terms), terms specification of the form “first*second” is same as __________
a) first+second
b) first:second
c) first+second+first:second
d) first:second+second:first
Answer: c
Clarification: A terms specification of the form “first + second” indicates all the terms in first together with all the terms in second with duplicates removed.