Week 1 Probabilities and Interpretations

Question 1

define the two types of data

Answer 1

qualitative - non numeric

quantitative - numeric

Question 2

define the two types of quantitative data

Answer 2

discrete - data can only take certain values

continuous - data can take any value within a range

Question 3

what is the first step for data visualisation

Answer 3

Create the simplest graph that conveys the information you want to convey

Question 4

what is the 2nd step for data visualisation

Answer 4

consider the type of encoding object and attribute used to create a plot

Question 5

what is the 3rd step for data visualisation

Answer 5

focus on visualising patterns or on visualising details, depending on the purpose of the plot

Question 6

what is the 4th step for data visualisation

Answer 6

select a meaningful axis value

Question 7

what is the 5th step for data visualisation

Answer 7

data transformation and graph aspect ratios can be used to emphasize ratios of change

Question 8

what is the 6th step for data visualisation

Answer 8

plot overlapping points that allows density to become apparent

Question 9

what is the 7th step for data visualisation

Answer 9

use lines when connecting sequential data in time-series plots

Question 10

what is the 8th step for data visualisation

Answer 10

aggregate larger datasets

Question 11

what is the 9th step for data visualisation

Answer 11

keep axis ranges as similar as possible

Question 12

what is the 10th step for data visualisation

Answer 12

select an appropriate colour scheme

Question 13

when are central tendency values useful

Answer 13

describing data with single values

Question 14

define the arithmetic mean

Answer 14

it is the central measure that is the result of the sum of all terms divided by the number of terms

Question 15

what is the geometric mean

Answer 15

calculated as the N-th root of the product of the N elements in the datasets

Question 16

what is the harmonic mean

Answer 16

reciprocal of the arithmetic mean of the reciprocals of the data values

Question 17

what is the root mean square and its equation

Answer 17

the square root of the mean of sum of the squares of the data values
sqrt[ Σx^2 / n ]

Question 18

what is the median

Answer 18

the data value that separates the data into an upper and lower half

Question 19

what is the mode

Answer 19

the value that appears most frequently in a dataset

Question 20

what are the 7 measures of dispersion that can be used to characterise a dataset

Answer 20

variance/standard deviation
mean absolute deviation
skewness
kurtosis
covariance
correlation
covariance matrix

Question 21

what is variance and its equation

Answer 21

it is the spread of distribution
V(x) = 1 / N Σ(xi - μ)
μ is the true mean

Question 22

what is standard deviation in terms of variance

Answer 22

the square root of the variance

Question 23

what is the mean absolute deviation equation

Answer 23

MAD = 1/N ΣIxi - I

Question 24

what is skewness and its equation

Answer 24

measure of asymmetry of a distribution

γ = 1/σ^3 )^3> = 1/Nσ^3 Σ(xi -)^3

Question 25

what is kurtosis and its equation

Answer 25

measure of tailedness of a distribution | κ = 1/σ^4 )^4 - 3 = 1/Nσ^4 Σ(xi - )^4 - 3

Question 26

when are covariance, correlation and covariance matrix more useful as measures of dispersion

Answer 26

when dealing with multiple variables

Question 27

what is covariance and its equation

Answer 27

measure of the joint variability of two random variables | cov(x,y) = 1/N Σ(xi - )(yi - )

Question 28

what is correlation and its equation

Answer 28

it is the normalisation of covariance via standard deviation | p(x,y) = cov(x,y) / σxσy

Question 29

what is the covariance matrix

Answer 29

the combination of covariance in a matrix