Statistics Y10 Time Series and Probability

Question 1

what is a time series graph

Answer 1

line graph with time plotted on the x (horizontal) axis

Question 2

what is the purpose of a trend line

Answer 2

• show general trend of data
• used to make predictions

Question 3

how to draw a trend line

Answer 3

• by eye
• about same number of points above and below

Question 4

what is the general trend

Answer 4

the way that the data changes over time

Question 5

what are dashed lines for on a graph

Answer 5

indicate that the values between the points have no meaning

Question 6

what variations might there be in a time series

Answer 6

• general trend
• seasonal variations

Question 7

what are seasonal variations

Answer 7

variations in a time series following a regular pattern

Question 8

calculate n-point moving average

Answer 8

Σx / n

Question 9

where to plot n-point moving average

Answer 9

(n+1) / 2 on x axis

Question 10

calculate seasonal variation

Answer 10

actual value - trend value

Question 11

calculate mean seasonal variation

Answer 11

Σ S.V.s for that season / n

Question 12

calculate predicted value (with seasonal variations)

Answer 12

trend value + mean seasonal variation

Question 13

what is the average seasonal effect

Answer 13

mean seasonal variation

Question 14

what is probability

Answer 14

a numerical measure of the chance of an event happening

Question 15

what if P(A) = 0

Answer 15

A is impossible to happen

Question 16

what if P(A) = 1

Answer 16

A is certain to happen

Question 17

what if P(A) = 0.5

Answer 17

chance of A happening is evens

Question 18

calculate probability when all outcomes are equally likely

Answer 18

no. of successful outcomes / total no. of outcomes

Question 19

calculate expected frequency of event A

Answer 19

P(A) * no. of trials

Question 20

calculate risk of an event

Answer 20

no. of trials where event occurs / total no. of trials

Question 21

calculate absolute risk of event A

Answer 21

P(A)

Question 22

calculate relative risk

Answer 22

risk for those in group / risk for those not in group

Question 23

what is absolute risk

Answer 23

the probability of a negative event happening

Question 24

what is relative risk

Answer 24

how many times more likely an event is to occur for one group compared to another group

Question 25

what is the sample space

Answer 25

the list of all possible outcomes

Question 26

what is a sample space diagram

Answer 26

tables used to represent the sample space

Question 27

when are sample space diagrams applicable

Answer 27

when all outcomes are equally likely

Question 28

what hapens as nuimber of trials increases

Answer 28

estimated probability gets closer to the true value

Question 29

what does a venn diagram need

Answer 29

* a box * (interlocking) circles * labels

Question 30

what does P(A) mean

Answer 30

probability of event A happening

Question 31

what does P(A∩B) mean

Answer 31

probability of event A and event B occuring

Question 32

what does P(A∪B) mean

Answer 32

probability of either event A or event b occuring

Question 33

what does P(A') mean

Answer 33

probability of event a not happening (complement of event A)

Question 34

calculate P(A')

Answer 34

1 - P(A)

Question 35

what are mutually exclusive events

Answer 35

events that cannot happen at the same time

Question 36

what are mutually exhaustive events

Answer 36

events that contain all possible outcomes

Question 37

calculate P(A∪B)

Answer 37

P(A) + P(B) - P(A∩B) (general addition law)

Question 38

what are independent events

Answer 38

events whose outcomes do not affect eachother

Question 39

calculate P(A∩B) for independent events

Answer 39

P(A) * P(B)

Question 40

what does P(A|B) mean

Answer 40

probability of event A happening given event B has happened

Question 41

calculate P(A|B)

Answer 41

P(A∩B) / P(B)

Question 42

calculate P(A|B) for independent events

Answer 42

P(A)