Stats

Question 1

How does Quota sampling work
Name one advantage and one disadvantage

Answer 1

Take a certain number from each category according to the size of each group in the population
Ad: all categories are represented
Disad: Not random so can lead to bias

Question 2

How does stratified sampling work
One advantage
One disadvantage

Answer 2

Sample data from each strata that is proportional to the population sizes
Adv : sample accurately reflects the population , selection is random
Disad : time consuming , depends on sampling frame available

Question 3

how does systematic sampling work
one advantage
one disadvantage

Answer 3

number every piece of data in the population then use random number generator to take a starting point, select every nth price of data

ad: random so less likely to lead to bias
disadv : need sampling frame

Question 4

how does opportunity sampling work
one advantage
one disadvantage

Answer 4

pick the data as it becomes available
adv: easy and quick (cheap)
disadv : not random , can lead to bias

Question 5

how does simple sampling work
one advantage
one disadvantage

Answer 5

number every piece of data in the population , use number generator to pick he numbers in the sample and keep going until you have your sample
Adv : random and less likely to be biased, each piece of data has an equal chance of being picked
disadv : requires a sampling frame

Question 6

if you have outliers which value of the average and which measure of the spread would be best to use

Answer 6

the median as the mean is distorted by extreme values

interquartile range as this is not affected by outliers - represents the middle 50%

Question 7

which value of the average and measure of the spread is most accurate and why

Answer 7

the mean and standard deviation as both measures include every value

Question 8

is the explanatory variable the x or y values

Answer 8

x values

Question 9

is the response variable the x or y values

Answer 9

y values

Question 10

if a line of regression y = 17.0 + 14x represents the relationship between the percentage (x%) of cocoa solids and the price (y pence ) of different chocolate , interpret the value 15.4

Answer 10

for every 1% more cocoa that the chocolate contains, the price can be increased by 15.4 pence

Question 11

if the relationship between the variables is p on n, is the linear regression line
p = an +b
or
n = ap + b

Answer 11

p = an + b

Question 12

where data is coded what is the mean affected by

Answer 12

addition / subtraction
multiplication / division

Question 13

continuous data ….

Answer 13

can take every value

Question 14

where data is coded what is the standard deviation affect by

Answer 14

multiplication / division

Question 15

discrete data is ….

Answer 15

data that can only take specific values e.g shoe size

Question 16

in large data set which UK locations are on the coast (windy )
north to south

Answer 16

Leuchars, Hurn, Camborne

Question 17

in the large data set which worldwide locations are on the coast

Answer 17

Jacksonville and Perth

Question 18

in the large data set what is the daily maximum gust measures in and give a definition of what this means

Answer 18

Knots
1 knot = 1.15 mph

Question 19

in the large data set what the only 3 categories of data where the data is continuous

Answer 19

daily mean rainfall
daily hours of sunshine
daily max temperature

Question 20

helpful histogram formula

Answer 20

area = k x frequency

Question 21

what is the definition in words of the standard deviation

Answer 21

the average distance every value is away from the mean

Question 22

for a hypothesis test that uses binomial distribution what are the null and alternative hypothesis if you are testing a two tailed test

Answer 22

H0 : p = p
H1 : not equal

Question 23

for a hypothesis test that is testing positive correlation what are the null and alternative hypotheses

Answer 23

H0 : row / p =
H1 : row/p > 0

Question 24

for a hypothesis test that is testing to see if the mean has decreased, what are the null and alternative hypotheses

Answer 24

H0 : u =
H1 : u<

Question 25

if you are using the normal approximation to a binomial distribution. x-b (10,0.2) and find P(X>3), what is the probability for the normal distribution

Answer 25

contribunitety correction P (x>3) includes the values 4,5,6,.....10 P(Y>3.5)

Question 26

hypothesis test for a mean using the ND, and the ND is K-N (120,5) if a sample is taken of 25 values, what ND do you use for the test and new value for the standard deviation

Answer 26

mean stays the same SD 5 / 25

Question 27

ACTUAL significance level of a hypothesis test , what are they asking for

Answer 27

the actual probability of the critical region , E.g. if the significance level is 0.05 but the probability of the critical region if P(X=5) = 0.0223 is the actual significance level

Question 28

when doing a two tailed hypothesis test what do you need to Ensure you always do first

Answer 28

divide the significance by 2

Question 29

what type of question means you have to use the standard Normal distribution Z-N(0,1^2)

Answer 29

when you have a missing mean of SD or both

Question 30

when trying to find the mean or SD using Z-N(0,1^2), what is the key formula

Answer 30

z= X - u / SD

Question 31

what is the general formula for finding out probabilities with the binomial distribution using SIGMA

Answer 31

upper lower and using the binomial C

Question 32

if you using the linear regression line to make a prediction what, what the two things you need to watch for

Answer 32

are there values close by ( extrapolation or interpolation) if extrapolation not reliable if you are using the independent variable (x) to predict the dependent variable (y)

Question 33

with vectors what is the formula that will give you the position vector of the final position, where the object does not start at the origin

Answer 33

r1 = r0 +s

Question 34

if string is inextensible what are you able to assume

Answer 34

acceleration is equal

Question 35

the object is moving is moving in the direction of 5i - 2j

Answer 35

velocity = K(5i - 2j)

Question 36

if the string is LIGHT what are you able to assume

Answer 36

tension is equal

Question 37

if an object is positioned south east what does this mean

Answer 37

r = K( i - j )

Question 38

other than resistance what may affect an object travelling in air due to gravity

Answer 38

spin of the object, dimensions of the object, wind affects