Statistics

Question 1

F (x) = f/n

Answer 1

Relative frequency = frequency/ total number of data

Question 2

CDF plot

Answer 2

Fx against data point

Question 3

What does the gradient of a CDF plot mean?

Answer 3

The steepest part of CDF plot corresponds to most number of data points. Shallower CDF -> low number of data points

Question 4

Skewness?

Answer 4

Which way the curve leans how asymmetrical it is

Question 5

Positive skew

Answer 5

Skews to the left

Question 6

Negative skew

Answer 6

Skews right

Question 7

Interquartile range?

Answer 7

Difference between third quartile and first quartile

Question 8

Sample space?

Answer 8

The set Ω of all possible outcomes of an experiment

Question 9

Event?

Answer 9

A sub-set A of the sample space A c Ω

Question 10

Α n B?

Answer 10

A and B occurring together (intersection)

Question 11

A u B

Answer 11

A or B occurring (union)

Question 12

_
A?

Answer 12

Not A (complement)

Question 13

Mutually exclusive?

Answer 13

Events cannot occur at same time

Question 14

Independent?

Answer 14

Event is not affected by previous events

Question 15

Dependent?

Answer 15

Event is affected by other event

Question 16

Permutations?

Answer 16

Order of outcome is important

Question 17

Combinations?

Answer 17

Order of outcomes is not important

Question 18

P(A|B)?

Answer 18

Probability of A given that B has already occurred

Question 19

P(A|B)P(B) = P(B|A)P(A) = ?

Answer 19

P(A n B)

Question 20

What does it mean if P(A|B) = P(A)?

Answer 20

Events A and B are independent

Question 21

Partitioned sample space?

Answer 21

The events are non-empty, non- overlapping whose union forms the whole sample space

Question 22

ΣP(B|A)P(A) = ? (Total probability law)

Answer 22

P(B)

Question 23

P(A|B)P(A) / P(B) = ? (bayes law)

Answer 23

P(A|B)

Question 24

P(A|B n C) P(B|C) P(C) = ?

Answer 24

P(A n B n C)

Question 25

Sx^2 = 1/(n-1) Σ(xi-x~)^2

Answer 25

Sample variance
Sample deviation = Sx
N= number of data points
x= value (each one)
x~= mean

Question 26

Vx= Sx/ x~

Answer 26

Coefficient of variation = standard deviation/ mean

Question 27

dx=1/n * Σ|xi-x~|

Answer 27

Mean absolute deviation = dx
n= number of data points
xi = data points
x~= mean

Question 28

Unbiased skewness= (n-1)/ (sqrt(n)*(n-2)(σ^3) * Σ(xi-x~)^3

Answer 28

n= number of data points
σ=standard deviation
xi= data point
x~ = mean

Question 29

Biased skewness = (1/n) * Σ(xi-x~)^3 / σ^3

Answer 29

n= number of data points
xi= data point
x~ = mean
σ= standard deviation

Question 30

What order is mode median and mean for positive skewness?

Answer 30

Mode - median - mean

Question 31

In what order is mode median and mean for a symmetric curve?

Answer 31

All equal

Question 32

In what order is mode median and mean for negative skewness?

Answer 32

Mean-> median -> mode

Question 33

cov= 1/(n-1) Σ(xi-x~)(yi-y~)

Answer 33

Sample convergence
n= number of data points
xi= each x point
x~ = mean x
yi= y point
y~ = y mean

Question 34

Cxy =1/(n-1) Σ(xi-x~)(yi-y~) / SxSy

Answer 34

Cxy= sample correlation coefficient (has to be between -1 and 1)
n= number of points
xi= x point
x~ = x mean
yi= y point
y~ = y mean
Sx= x standard deviation
Sy= y standard deviation

Question 35

What does Cxy= -1 mean?

Answer 35

Perfect negative linear correlation

Question 36

What does Cxy= 0 mean?

Answer 36

No correlation

Question 37

What Cxy= 1 mean?

Answer 37

Perfect positive linear correlation

Question 38

Variable?

Answer 38

A quantity that can vary

Question 39

Random?

Answer 39

The result will be the outcome of a random experiment

Question 40

Discrete?

Answer 40

Has a limited number of outcomes

Question 41

Continuous?

Answer 41

Has a limitless number of outcomes in between two points

Question 42

PDF=f(x) = dF(x)/ dx

Answer 42

Probability density function = the gradient of CDF plot

Question 43

What is the area under a CDF plot?

Answer 43

1

Question 44

The steepest part of a CDF plot is where on a PDF (probability density function) plot?

Answer 44

The peak