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5.01 Reading and interpreting time series graphs

Worksheet
Time series graphs
1

Consider the graph below:

a

State the explanatory variable.

b

Identify the underlying trend in the data as increasing, decreasing, or constant.

2

Consider the graph below:

a

Which year had more ice: 2005 or 2007?

b

What can be concluded about the amount of sea ice as time passes?

c

Which month is the warmest in the Arctic?

3

Using the graph below, list the months where the rainfall in London was less than the rainfall in Berlin:

4

The graph below shows energy usage in two countries over several years:

State whether each of the following statements is true or false:

a

Australia used more energy in 2012 than it did in 2004.

b

The United Kingdom used more energy in 2011 than in 2006.

c

The United Kingdom is cutting back on its energy use overall.

d

From 2004 to 2012, the United Kingdom's usage decreased by more than Australia's usage increased.

e

The graph does not give us any information about how the type of energy being used.

f

The graph does not give us any information about energy use per capita.

g

From the graph we can assume that the population of the United Kingdom is declining.

h

We would need more information to comment on the energy usage per capita, and hence draw a conclusion about how well either country is doing about reducing primary energy usage.

5

The graph below shows the change in Apple Inc.'s share price along with major releases of its products:

Using the graph, state whether each of the following is true or false:

a

The price of Apple’s products always increased.

b

The release of Apple products promoted a general trend upwards in the share price.

c

Apple’s share price increased by the same amount each year.

6

The graph below shows the change in Australian stock prices (in red) and US stock prices (in blue) over several years:

a

Identify the underlying trends of the US and Australian stock prices from October 2002 to October 2006 as increasing, decreasing, or constant.

b

During October of which year does the trend first change direction?

7

Consider the following graph:

a

Identify the underlying trend as increasing, decreasing, or constant.

b

On what date does an outlier appear to occur?

c

Count the approximate number of days in one cycle.

8

The following graph shows the number of US dollars that one Australian dollar could buy over a 5 year period:

a

Identify the underlying trend as increasing, decreasing, or constant.

b

During the 5 year period, the first irregular and sustained fluctuation occurred in what year?

c

Compare the 5 year graph to the 10 year graph below:

During what year did the value of the Australian dollar crash?

9

For each of the given time series graphs, answer the following:

i

Identify the underlying trend of the data as increasing, decreasing, or constant.

ii

State the number of points per cycle.

a
2
4
6
8
10
12
x
5
10
15
20
25
30
y
b
2
4
6
8
10
12
x
5
10
15
20
25
30
y
c
2
4
6
8
10
12
14
16
x
10
12
y
d
2
4
6
8
10
12
x
10
20
30
40
50
60
70
80
y
e
2
4
6
8
10
12
14
16
x
-100
-80
-60
-40
-20
20
40
60
80
100
120
140
160
y
10

Consider the following time series graph:

a

Identify the underlying trend as increasing, decreasing, or constant.

b

Calculate the number of seasons per cycle.

Company Sales 2002 - 2016 (millions)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
10
20
30
40
50
60
11

Consider the following time series graph:

a

Identify the underlying trend as increasing, decreasing, or constant.

b

State the number of seasons per cycle.

c

In which month does the cycle peak?

d

Which month is usually the lowest season? Was there an exception to this?

12

Consider the following time series graph, which shows the average hours worked per week recorded for each month:

a

Identify the underlying trend for the data as increasing, decreasing, or constant.

b

State the number of seasons per cycle.

c

State the number of the month in which there is an outlier.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
x
10
20
30
40
50
60
70
13

For each of the following tables of time series data:

i

Plot a time series graph for the data.

ii

State the number of seasons per cycle.

iii

Identify the underlying trend of the data as increasing, decreasing, or constant.

iv

State the time period that appears to be an outlier, if there is one.

a
Time Period123456789101112
Data510181112071322101525
b
Time Period123456789101112
Data7510095135609090110557595105
c
MonthWatch time (hours)
\text{Jan \rq17}81
\text{Apr \rq17}78
\text{Jul \rq17}75
\text{Oct \rq17}74
\text{Jan \rq18}80
\text{Apr \rq18}77
\text{Jul \rq18}75
\text{Oct \rq18}73
\text{Jan \rq19}81
\text{Apr \rq19}78
\text{Jul \rq19}75
\text{Oct \rq19}74
d
\text{Month}\text{Number of bags (\rq000s)}
\text{Dec \rq05}9.5
\text{Jun \rq06}9.1
\text{Dec \rq06}9.7
\text{Jun \rq07}9.5
\text{Dec \rq07}9.9
\text{Jun \rq08}8.2
\text{Dec \rq08}8.5
\text{Jun \rq09}8.3
\text{Dec \rq09}8.5
\text{Jun \rq10}8
\text{Dec \rq10}8.1
\text{Jun \rq11}7.7
\text{Dec \rq11}7.3
\text{Jun \rq12}7.5
\text{Dec \rq12}7
14

The local police station records the number of speeding fines issued each quarter. The following table has the data for each quarter from 2012 to 2014:

PeriodTimeNumber of speeding finesPercentage of yearly mean
1\text{March 2012}2083.33\%
2\text{June 2012}28116.67\%
3\text{September 2012}36150\%
4\text{December 2012}1250\%
5\text{March 2013}2481.36\%
6\text{June 2013}35118.64\%
7\text{September 2013}42142.37\%
8\text{December 2013}1757.63\%
9\text{March 2014}3289.51\%
10\text{June 2014}39109.09\%
11\text{September 2014}51142.66\%
12\text{December 2014}2158.74\%
a

Plot a time series graph for the number of fines recorded each quarter against the period.

b

Identify the underlying trend of the data as increasing, decreasing, or constant.

15

From the beginning of 2012, the number of new houses built in the suburb of Woodford was recorded and figures are released every four months.

The table shows the data from the beginning of 2012 to the end of 2015:

a

Plot a time series graph for the data.

b

Does the data appear to be seasonal?

c

Identify the underlying trend of the data as increasing, decreasing, or constant.

d

State the number of seasons per cycle.

Time periodHouses built
\text{April }2012103
\text{August }201292
\text{December }2012105
\text{April }201399
\text{August }201388
\text{December }2013104
\text{April }201493
\text{August }201485
\text{December }2014103
\text{April }201593
\text{August }201583
\text{December } 201596
16

The following table shows the sales in thousands of dollars for a particular company:

Year2010201120122013201420152016
Profit (in thousands of dollars)55626058647683
a

Plot a time series graph for the data.

b

Identify the underlying trend of the data as increasing, decreasing, or constant.

c

Find the percentage growth in profit from 2010 to 2016. Round your answer to the nearest percent.

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Outcomes

3.2.1.1

construct time series plots

3.2.1.2

describe time series plots by identifying features such as trend (long-term direction), seasonality (systematic, calendar-related movements) and irregular fluctuations (unsystematic, short-term fluctuations), and recognise when there are outliers, e.g. one-off unanticipated events

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