Math Problem Statement

Using simple moving averages and the following time series data, respond to each of the items.  

Period

Demand

1

130

2

122

3

121

4

112

5

143

6

105

7

116

8

118

9

142

10

125

  Click here for the Excel Data File   b. Compute all possible forecasts using a six-period simple moving average model. (Round your answers to 1 decimal place.)

Solution

To calculate the six-period simple moving average (SMA) forecast for each period, you take the average of the demand values from the previous six periods. The forecast can only begin after the first six periods of data are available.

Here are the steps for calculating the six-period SMA for each period from the 7th onward:

Data Provided:

PeriodDemand
1130
2122
3121
4112
5143
6105
7116
8118
9142
10125

Steps:

  1. Calculate the six-period SMA for Period 7: SMA for Period 7=130+122+121+112+143+1056=7336122.2\text{SMA for Period 7} = \frac{130 + 122 + 121 + 112 + 143 + 105}{6} = \frac{733}{6} \approx 122.2

  2. Calculate the six-period SMA for Period 8: SMA for Period 8=122+121+112+143+105+1166=7196119.8\text{SMA for Period 8} = \frac{122 + 121 + 112 + 143 + 105 + 116}{6} = \frac{719}{6} \approx 119.8

  3. Calculate the six-period SMA for Period 9: SMA for Period 9=121+112+143+105+116+1186=7156119.2\text{SMA for Period 9} = \frac{121 + 112 + 143 + 105 + 116 + 118}{6} = \frac{715}{6} \approx 119.2

  4. Calculate the six-period SMA for Period 10: SMA for Period 10=112+143+105+116+118+1426=7366122.7\text{SMA for Period 10} = \frac{112 + 143 + 105 + 116 + 118 + 142}{6} = \frac{736}{6} \approx 122.7

Summary of Six-Period SMA Forecasts:

PeriodSMA Forecast
7122.2
8119.8
9119.2
10122.7

These are the six-period simple moving average forecasts for periods 7 through 10.

Would you like any further explanation or help with additional calculations?


Follow-up Questions:

  1. What is the formula for a simple moving average with a different period length?
  2. How would you compute a weighted moving average?
  3. Can you explain the significance of moving averages in forecasting?
  4. What is the impact of using a longer period for the moving average on the forecast accuracy?
  5. How does the simple moving average compare to exponential smoothing?
  6. What are the advantages of using a simple moving average for forecasting?
  7. How could you apply a moving average to seasonal data?
  8. What happens if there is a significant outlier in the data when using a moving average?

Tip: The simple moving average smooths out short-term fluctuations and highlights longer-term trends, but it can lag behind sudden changes in the data.

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Math Problem Analysis

Mathematical Concepts

Time Series Analysis
Simple Moving Average (SMA)

Formulas

Simple Moving Average formula: SMA = (Sum of Demand values over n periods) / n

Theorems

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Suitable Grade Level

Graduate Level