# Data collected over a period of time Example Data seems pretty random!!

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Data collected over a period of time

Example

Data seems pretty random!!

Some go up,

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

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

Drawing a graph helps a bit

You can see the general trend

Looking closer you can see a cyclic nature to this data

Every third value is a low one

We want to be more specific about the general trend

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

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

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

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

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

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

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

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

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

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

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

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

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

We now have a STRAIGHT line through the data,

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

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