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The data for this question given in the table below come from the sample data folder of

MINITAB. The data give you the monthly number of people employed $($in units of $1000)$ in

the retail trade industry in the state of Wisconsin from January $1970$ to December $1974.$ Copy

this timeseries data into an excel spreadsheet in your home area first before you start your

analysis. You can use Excel to answer this question.

$($a$)$ Draw a time series plot of the data and comment on any noticeable patterns.

$($b$)$ Describe an appropriate time series model for this data, giving your reasons, and obtain

estimates of the components of your model using the decomposition method.

$($c$)$ Using your model forecast the monthly number of people employed in the retail trade

industry in Wisconsin for each month of $1975.$ Clearly show all your working and steps

you used in the calculation of your forecast. Discuss the accuracy of your forecast.

$($d$)$ Discuss the limitations of the decomposition method compared with the exponential

smoothing method.