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Looking at the time-series plot of data (pictured), and looking at the table (pictured), what method and why has been chosen for the analysis that has been started on the table shown?

I'm struggling to figure this out, is it multiplicative decomposition, additive, or?

Main question I need answered is - “with reference to the graph, justify the chosen method of analysis that has been started on the table shown”

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  • $\begingroup$ ad hoc comes to mind . $\endgroup$ – IrishStat Jan 11 at 9:54
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The table contains 3 methods of analysis:

  1. "Moving Average": Simply the mean of the closest 4 data values. Example: The first value is $290.75 = (207.5 + 265.5 + 401 + 289) / 4$. This is called a moving average with centered window of size four; as for any point in time it takes the closest four datapoints to the left and the right of it and then moves in time. This smoothes the original data.

  2. "Centered Moving Average": This is a moving average of the moving average calculated above. Example: The first value is $296.4375 = (290.75 + 302.125)/2$

  3. Trend Line: This is a linear regression. The slope is $15.5$ and the intercept $253.5$. They have been calculated based on the moving average as it seems, or at least not on the data directly (as I get different values for slope and intercept on the data directly).

It has supposedly been started to extract the "general trend" of the time series, as it seems. Probably for the purpose of predicting/forecasting the next values (looking at the second last column).

There is no time-series decomposition, or any such thing (neither multiplicative nor additive, as it seems).

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  • $\begingroup$ So with reference to the graph, the chosen method of analysis that’s been started on that worksheet is: moving average and trend line? Also, is there one single analysis name for this? $\endgroup$ – JackB Jan 9 at 0:41
  • $\begingroup$ Exactly. Doesn't have another name at least to my knowledge. $\endgroup$ – Denwid Jan 9 at 19:02
  • $\begingroup$ Ok. Which one of these methods does the graph support? I suppose the trend line is a result of the graph. So the graph is based on MA? $\endgroup$ – JackB Jan 13 at 23:16
  • $\begingroup$ Graph is the sales data plotted directly. $\endgroup$ – Denwid Jan 14 at 5:38
  • $\begingroup$ Awesome. Alternatively could it be a Regression or correlation analysis? $\endgroup$ – JackB Jan 17 at 0:12

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