Stats

Question 1

Variance

Answer 1

Standard deviation squared

Question 2

No Correlation

Answer 2

r=0

Question 3

Weak correlation

Answer 3

r<0.5

Question 4

Moderate correlation

Answer 4

0.5<r<0.75

Question 5

Strong correlation

Answer 5

0.75<r<1

Question 6

Lower outlier

Answer 6

X < LQ - ( 1.5 x IQR )

Question 7

Upper Outlier

Answer 7

X > UQ + ( 1.5 x IQR )

Question 8

Convenience Sampling

Answer 8

• selecting most easily accessible members

Pros: fast, cheap easy

Cons: does not represent whole population, biassed sample, not replicable

Question 9

Simple Random Sampling

Answer 9

• each member of population has equal chance of being selected

Pros: no sampling bias, generalisability

Cons: time consuming

Question 10

Systematic Sampling

Answer 10

• when participants are selected using a fixed periodic interval

Pros: better population coverage, simple & easy

Cons: could be biased if there is periodic pattern

Question 11

Stratified Sampling

Answer 11

• dividing the population into smaller groups based on characteristics. Then randomly selecting

Pros: ensures proper representation, more precise population estimates

Cons: if groups are not mutually exclusive there could still be bias

Question 12

mode

Answer 12

most common number that appears in data

Question 13

median

Answer 13

middle value in list of numbers

Question 14

mean

Answer 14

the average

Question 15

modal class

Answer 15

the interval within a set of data with the most number of data points

Question 17

1 standard deviation

Answer 17

68% of data

Question 18

1 standard deviation

Answer 18

68% of data

Question 19

2 standard deviation

Answer 19

95% of data

Question 20

3 standard deviation

Answer 20

99.7% of the data

Question 21

Union

Answer 21

• u
• P(AuB)
• ‘or’

Question 22

Intersection

Answer 22

• n
• P(AnB)
• ‘and’

Question 23

Dash or ‘ meaning

Answer 23

• without
• if ‘ is on outside of probability brackets then distribute it to all the terms

e.g. P(AnB)’
= P(A’uB’)

the n (intersection) turns to u (union) with ‘

& vice versa

Question 24

binomial theorem formula to memorise for binomial distribution : the probability: P(X=r)

Answer 24

P(X=r) = nCr (P^r) (1-P)^(n-r)

Question 25

if the mean of a data set is x then each term in the data set is added y what is the new mean?

Answer 25

x+y (mean + constant added to data set) (e.g. if mean is 5, then 10 is added to every term in data set, new mean =15)

Question 26

if the std deviation of a data set is d then each term in the data set is added y what is the std deviation?

Answer 26

d (std deviation stays the same) (e.g. if std deviation is 2, then 10 is added to every term in data set, new std deviation =2)

Question 27

if the mean of a data set is x then each term in the data set is multiplied z what is the new mean?

Answer 27

xz (mean x multiple) (e.g. if mean is 5, then 10 is multiplied to every term in data set, new mean is =50)

Question 28

if the std deviation of a data set is d then each term in the data set is added z what is the std deviation?

Answer 28

dz (std deviation x multiple) (e.g. if std deviation is 2, then 10 is multiplied to every term in data set, new std deviation =20)