Initial analysis of the data

Question 1

What are all R commands?

Answer 1

Functions

Question 2

how do you get data into R

Answer 2

Read.table()

read.csv()

Question 3

how do you get data out of R

Answer 3

write.csv()

Question 4

what is nominal data?

Answer 4

names of things

Question 5

what is ordinal data?

Answer 5

ordered names

Question 6

what is interval data?

Answer 6

numeric with no true zero (Celsius)

Question 7

what is ratio data?

Answer 7

numeric with true zero (kelvin)

Question 8

which 2 data classifications are categorical or discreet?

Answer 8

nominal and ordinal

Question 9

which 2 data classifications are continuous variables?

Answer 9

interval and ratio

Question 10

what is a number?

Answer 10

can have decimals

Question 11

what is a integer?

Answer 11

whole number

Question 12

what is a character?

Answer 12

not a number

Question 13

what is a vector?

Answer 13

set of values of the same data (combine function c() )

Question 14

what is a list?

Answer 14

collection of different vectors or other data structures

Question 15

what is a factor?

Answer 15

categorical variable

fixed set of values

Question 16

what are arrays?

Answer 16

n-dimensional homogeneous data types

Question 17

what are matrices?

Answer 17

2D and numeric

Question 18

what is a data frame?

Answer 18

a list but all component vectors are same length

Question 19

what is the R code for viewing the data?

Answer 19

head()

tail()

Question 20

what is the r code for viewing a summary of the data?

Answer 20

summary()

Question 21

what is the r code for computing basic statistics?

Answer 21

sd()
var()
range()
IQR()

Question 22

What is the r code for the correlation?

Answer 22

cor()

Question 23

what does visualisation give you?

Answer 23

more holistic picture of the data

Question 24

what are summary statistics?

Answer 24

mean vs median
standard dev
quartiles
correlations

Question 25

what is Anscombe's Quartet?

Answer 25

4 sets of data based on standard statistics

Question 26

what does hist() mean in R?

Answer 26

Plot a histogram

Question 27

what do missing values suggest?

Answer 27

dirty data

Question 28

what is the best first visualisation of 2 variables?

Answer 28

scatter plots

Question 29

what is a box and whisker plot?

Answer 29

a plot that shows the centre box of the data (50%)

Question 30

why use a pairwise plot?

Answer 30

visually represent data relationships | examines relationship quickly

Question 31

What does time series analysis have to have?

Answer 31

the same time period

Question 32

what is the null hypothesis

Answer 32

no difference

Question 33

what is the alternate hypothesis

Answer 33

there is a difference

Question 34

what is the difference of means?

Answer 34

the overlap of 2 data sets

Question 35

what is the p value?

Answer 35

the area under the tails of curve

Question 36

if the p value is less than 0.5 what do you do?

Answer 36

reject the null hypothesis

Question 37

student t-test assumes both populations are - a) normally distributed b) not normally distributed

Answer 37

a)normally distributed

Question 38

what do you use if the data is not normally distributed?

Answer 38

wilcoxon rank sum test

Question 39

what are the steps in hypothesis testing?(3)

Answer 39

calculate test statistic calculate p value if p value less than 0.5 then reject

Question 40

what is a type 1 error (false positive)

Answer 40

reject null hypothesis and the null hypothesis is true

Question 41

what is a type 2 error (false negative)

Answer 41

accept null hypothesis and null hypothesis is false

Question 42

what is significance?

Answer 42

the probability of a false positive

Question 43

what is power?

Answer 43

the probability of a true positive

Question 44

what is effect size?

Answer 44

the actual magnitude of the result

Question 45

what does ANOVA stand for?

Answer 45

analysis of variance

Question 46

what is ANOVA?

Answer 46

Generalisation of the difference of means

Question 47

what percentage of confidence interval do most people use?

Answer 47

95%

Question 48

would you visualise before or after model building?

Answer 48

before