Interactive practice questions
A hairdressing salon at a local shopping centre records the number of customers per day and the results are shown in the graph below.
Comment on the trend and seasonality of the data. Select all that apply.
There is a downwards trend over time.
The trend is that the numbers stay stable.
There is an upwards trend over time.
There are $4$4 seasons in a cycle.
There are $5$5 seasons in a cycle.
The table below shows some time series data where $t$t represents time.
A cat boarding kennel records its number of boarders every $4$4 months (tri-annually) ending at January, May and September.
A ballet company performed $4$4 times a week for four weeks at the Perth Concert Hall which is able to seat $1731$1731 patrons. To break even the attendance must be more than $60%$60% of maximum capacity. The attendance at the daily performances are shown in the table below.
Outcomes
ACMGM088
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; for example, one-off unanticipated events
ACMGM089
smooth time series data by using a simple moving average, including the use of spreadsheets to implement this process
ACMGM090
calculate seasonal indices by using the average percentage method
ACMGM091
deseasonalise a time series by using a seasonal index, including the use of spreadsheets to implement this process
ACMGM092
fit a least-squares line to model long-term trends in time series data