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Published byTessa Wormald Modified over 2 years ago

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Data collected over a period of time

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Example

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Data seems pretty random!!

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Some go up,

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Data seems pretty random!! Some go up, some down

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Data seems pretty random!! Some go up, some down What the?

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Drawing a graph helps a bit

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You can see the general trend

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Looking closer you can see a cyclic nature to this data

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Every third value is a low one

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We want to be more specific about the general trend

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We want to be more specific about the general trend, so we calculate a MOVING AVERAGE

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Our data seems to occur in groups of three, so we will use a 3 POINT moving average

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How does it work? Calculate the average of the first group of 3 points

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3. Calculate the average of the second 3 points 1. Drop the first Monday 2. Pick up the second Monday

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3. Calculate the average of the third group of 3 points 1. Drop the first Wednesday 2. Pick up the second Wednesday

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3. Calculate the average of the fourth group of 3 points 1. Drop the first Friday 2. Pick up the second Friday

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Keep moving the averages down until you have run out of points to include

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Remember… Every moving average needs to include one of each type of value, ie 1 x Monday 1 x Wednesday 1 x Friday in some order

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Plotting this moving average on the original graph looks like this…

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The moving average looks much more linear than the raw data and can be used more effectively as a regression basis

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Using the Statistics Mode to calculate a linear regression for the moving average

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1. Using ONLY times that actually have moving averages, enter those time values into LIST 1

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Using the Statistics Mode to calculate a linear regression for the moving average 1. Using ONLY times that actually have moving averages, enter those time values into LIST 1 2. Enter the moving averages into LIST 2

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Using the Statistics Mode to calculate a linear regression for the moving average 1. Using ONLY times that actually have moving averages, enter those time values into LIST 1 2. Enter the moving averages into LIST 2 3. CALC – LINEAR REG

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We now have a STRAIGHT line through the data,

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We now have a STRAIGHT line through the data, and can use it to make predictions

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