Book - Chapter 3 basic analytics in r

Question 1

What is the function to import data

Answer 1

Read.csv

Question 2

What does the head function do

Answer 2

Examines the imported dataset

Question 3

What does the summary function do

Answer 3

Provide some descriptive statistics, such as mean and medium, for each data column

Question 4

When referring to a column in a dataset what symbol should you use

Answer 4

The $

Question 5

How would you plot linear regression

Answer 5

Lm

Question 6

What does our software use

Answer 6

Commandline interface

Question 7

How do you set a working directory

Answer 7

Set WD

Question 8

What are the categorical/qualitative attribute types

Answer 8

Nominal and ordinal

Question 9

What are the numeric/quantitative attribute types

Answer 9

Interval and ratio

Question 10

What are nominal data types

Answer 10

ZIP Codes
 nationality 
street names 
gender 
employee ID number 
true or false

Question 11

What is an ordinal data type

Answer 11

Ordered names for example
quality of diamonds
academic grades
magnitude of earthquakes

Question 12

What is interval data types

Answer 12

Numeric with no true zero for example Celsius or Fahrenheit

Question 13

What is ratio data type

Answer 13

Numeric with a true zero for example age or temperature in Kelvin

Question 14

What is a vector

Answer 14

Set of values of the same data type.

Question 15

What can you use to create vectors

Answer 15

The combined function

Question 16

What dimension is a vector

Answer 16

They are dimensionless

Question 17

What is a 2dimensional array

Answer 17

Matrix

Question 18

What is an array

Answer 18

N dimensional set of homogenous data type values

Question 19

What does the function nrow and nCol do

Answer 19

Define the number of rows and columns

Question 20

What is a DataFrame

Answer 20

Like a spreadsheet and list but all columns are the same length

Question 21

Can data frames stored different data types

Answer 21

Yes

Question 22

What is the list

Answer 22

A list is a collection of vectors and to be different lengths

Question 23

What is a factor

Answer 23

A set of categorical variables.

Fix set of values and use integer code to represent different values

Question 24

What does variance mean

Answer 24

The distance from means squared

Question 25

What does standard deviation mean

Answer 25

The square root of variance

Question 26

What does ranged mean

Answer 26

Minimum to maximum

Question 27

What is interquartile range

Answer 27

25% to 75% of the size order data

Question 28

Why do we visualise

Answer 28

To get a sense of the data

Question 29

What should we visualise

Answer 29

Mean versus median. Standard deviation. Quantiles. Correlations between variables

Question 30

What does anscombes quartet do.

Answer 30

Illustrates the importance of visualising data. Uses for data sets. Each day is to set is plotted as a scatterplot and then fitted with lines with the results of applying linear regression

Question 31

What should you do if the data is skewed

Answer 31

Logit

Question 32

What does bimodal mean

Answer 32

It has more peaks

Question 33

What is data cleansing

Answer 33

Eliminating dirty data

Question 34

What is a plot function q

Answer 34

Scatter plot where x is the index and y is the value

Question 35

What is a barplot function

Answer 35

Barplot with vertical and horizontal bars

Question 36

What is a dot chart

Answer 36

Cleveland dot plot

Question 37

What is a plot (density (data))

Answer 37

Density plot. A continuous histogram

Question 38

What is a stem function

Answer 38

Stem and leave plot

Question 39

How many variables can a scatter plot have

Answer 39

5

Question 40

What is a loess line do?

Answer 40

Fit a non linear line to the data

Question 41

What charts can be used to visualise multiple variables.

Answer 41

Barplot and dotchart

Question 42

When would you use a hexbinplot

Answer 42

When dealing with large data sets

Question 43

What is pairwise plot

Answer 43

A scatter plot matrix

Question 44

What is the seasonality effect?

Answer 44

If a small peak or fall happens the same time every year or time series

Question 45

What is the basic concept for hypothesis testing?

Answer 45

To form an assertion and test it with data

Question 46

What is the null hypothesis

Answer 46

No difference

Question 47

What does it mean if the regression coefficient is zero

Answer 47

The null hypothesis

Question 48

What is the basic testing approach

Answer 48

To compare the observed sample means

Question 49

What does a large absorb difference between the sample means indicate

Answer 49

That the null hypothesis should be rejected

Question 50

For the difference in means how can this be tested

Answer 50

Students t-test or Welches t-test

Question 51

What is students t-test

Answer 51

Assumes that distributions of two populations have equal but unknown variances

Question 52

In students t-test if each population is normally distributed with the same main and with the same variance what do you do

Answer 52

On the T city stick follows a T distribution with degrees of freedom

Question 53

If the observed value of t is far enough from zero what should you do

Answer 53

Reject the null hypothesis

Question 54

What is a significance level

Answer 54

The small probability

Question 55

What is the significance level of the test

Answer 55

The probability of rejecting no hypothesis, when the no hypothesis is actually true

Question 56

What is the normal significance level

Answer 56

0.05

Question 57

What is different in a two sided hypothesis test

Answer 57

It is necessary for the sum of probabilities and the both tales of the t-distribution to equal the significance level

Question 58

What is the P value

Answer 58

Area under the tail

Question 59

What is a confidence interval

Answer 59

Is an interval estimate of the population para meter or characteristic based on sample data

Question 60

How is the confidence interval used

Answer 60

It is used to indicate the uncertainty of a point estimate

Question 61

What is Wilcoxen tank sum test

Answer 61

Makes no assumption about the distributions of populations. Robust test for difference and means

Question 62

What is the type one error

Answer 62

Rejection of the null hypothesis when the normal hypothesis is true

Question 63

What is the Type II error

Answer 63

And acceptance of the null hypothesis when the no hypothesis is full

Question 64

What is significance

Answer 64

Probability of a full positive

Question 65

What is power

Answer 65

Probability of a true positive

Question 66

What is affect

Answer 66

The size of the observed difference

Question 67

What do you use it is more than two populations

Answer 67

A nova

Question 68

What does a nova stand for

Answer 68

Analysis of variance

Question 69

What is the F statistic in a nova

Answer 69

A measure of how different the means are relative to the variability within the group