时间数列分析

Bureau of Census in the 1950’s. It was brought to A-
B in the early 1960’s and has become the standard for
reporting sales.
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Why Time Series ?
• Beer sales are highly seasonal • It is very difficult to evaluate monthly sales over time.
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Seasonally Adjusted Sales =
Raw Sales X Selling Day Factor ÷ Seasonal Factor
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Raw Sales
How do time series work?
Selling Day Adjusted
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Selling Days
All other things being equal, sales in Aug-03 would decrease 4.8% because of one less selling day. In order to compare the two months Aug-03 sales will have to be adjusted up +4.8%.
0%
+21%
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More Misleading Growth Rates
-21%
+15%
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What are time series used for?
• At A-B we use time series to… – Assess current sales performance – Develop current year sales projections…PYE (projected year-end) – Forecast next year sales… develop budgets and monthly spreads – Other quantitative sales analysis
• Time series significantly improve decision making… – Allows us to take corrective action sooner – Allows us to take the right corrective action – Helps to establish appropriate sales objectives
பைடு நூலகம்
• Time Series technique statistically removes the effects of these two factors
• Time Series technique uses the X-11 procedure for seasonal
adjustments
– The X-11 procedure was developed by the U.S.
– Establish appropriate budgets for next year and estimate
monthly budget spreads
Time series analysis is the primary sales analysis technique at A-B
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Seasonally Adjusted
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Dissecting a Time Series Plot
STR’s; Ontario STC’s
Data Description … tells us the type of data plotted
• Uses of time series
– Assess current sales performance and evaluate the
effectiveness of sales programs
– Determine underlying sales trend and project year end sales
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Seasonality
• Seasonality is expressed as an index for a month compared to an average month.
• A month where sales were 20% higher than average would have a seasonal factor of 120.
时间数列分析
2020年7月16日星期四
Benefits and Uses of Time Series
• Benefits of time series – Monitor sales performance over time… remove variation in monthly sales caused by calendar differences and seasonality that can conceal potential problems with sales – Accurately determine the direction and rate of growth/decline in sales – Quickly identify changes in sales trends and correlate them to factors affecting sales… industry, company, competition – Improve decision making regarding sales and marketing actions
Irregular variations … shows us the impact of market place actions Trend Line … tells us the direction of sales based on past & present performance Annualized Sales … tells us how big the market is.
• A seasonal factor is computed and applied to the selling day adjusted sales
– This factor, when applied, gives you monthly data directly comparable to any other month … e.g. accurately compare June this year with May this year
• A month which was 10% lower than average would have a seasonal factor of 90.
No Seasonality
Strong Seasonality
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Adjusting Sales
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Time Series Analysis
• What is Time Series Analysis? • How are Time Series plots developed? • What are the advantages of Time Series Analysis? • What are Time Series used for?
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Assessing Sales Performance
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How is our YTD performance?
How do time series adjust sales ?
• A selling day adjustment factor for each month is computed and applied to the raw sales
– This factor allows you to compare months as if they had the same number of selling days … e.g. accurately compare the June this year vs. June last year
• But, if there was a significant market event or change, the year over year trends will be misleading
+50%
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Misleading Growth Rates