Getting started with regression techniques in SPSS

Transcription

1 Getting started with regression techniques in SPSS Jarlath Quinn Analytics Consultant Rachel Clinton Business Development

2 Premium, accredited partner to IBM specialising in the SPSS Advanced Analytics suite. Team each has 15 to 20 years of experience working in the predictive analytic space - specifically as senior members of the heritage SPSS team

3 Agenda Overview of regression techniques and linear relationships Performing a simple linear regression Using multiple linear regression to make predictions Predicting response likelihood with logistic regression

4 What do we mean by Regression? A family of statistical techniques used to predict outcomes and generate estimates for hundreds of applications Linear regression is used When the outcome is continuous (or scale) data The relationships between the fields can be described using straight lines Non linear regression Is used when the outcome itself is not linear (such as a category) Often takes the form of logistic regression

5 Where are regression techniques used? Modelling the relationship between promotion spend and revenue Estimating pollution levels following heavy rainfall Predicting tourism revenue based on exchange rates and air travel costs Predicting student test scores based on previous test results and peer-group performance Estimating website hits based on re-tweets and follower numbers Predicting sales of barbeques based on temperature forecasts

6 Regression to the mean

7 Regression to the mean *jittered points

8 Regression to the mean

9 Regression to the mean

10 Regression to the mean } The regression line is drawn so it that minimises the differences between the points and line itself ( this is called the line of least squares)

11 Regression to the mean * But be careful It is just an average after all *Anscombe s Quartet

12 Measuring linear relationships Pearson correlation values

13 Non-linear relationships Pearson correlation values

14 Correlations as percentages Correlation = x = = 73.8 % Correlation Squared = R Square 73.8%

15 From correlation to prediction How can we express linear relationships as predictive models?

16 How long does it take to cook a chicken?

17 How long does it take to cook a chicken? 7 minutes per pound plus 45 minutes 20 minutes per pound plus 20 minutes y = mx + c or y = a + bx

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19 Lets look at a demo of linear regression in IBM SPSS Statistics

20 How can we predict category outcomes?

21 Logistic regression Allows us to predict things that linear regression can t Such as Response to a marketing campaign Credit risk Whether a subscriber is likely to renew a service Risk of equipment failure How likely is it that a particular patient will be readmitted to hospital Whether a charity donor will switch to direct debit

22 Logistic regression But. These outcomes are not continuous numbers so standard linear regression won t work When the outcome consists of two categories we use binary logistic regression When the outcome has three or more categories we use multinomial logistic regression Logistic gets around the limitations of describing relationships with straight lines by using a special sigmoid curve

23 Probability of Responding Logistic regression Discount % 00

24 IBM SPSS Regression Module and R integration Using the SPSS Regression Module we can go beyond Linear Regression and unlock many other types of Regression functionality

25 Exclusive Smart Vision bundle offers Regression add-on pack If you already have SPSS base and add the regression module to your licence 1 user perpetual licence + 1 st year support + 1 day personalised training 2,900 (+ VAT) Saving 500 on IBM list price Offer code SVRegSP001 SPSS & Regression starter pack If you do not have SPSS base licence already. Purchase Base & Regression 1 user perpetual licence + 1 st year support + 2 days personalised training 4,229 (+ VAT) Saving 1,000 on IBM list price Offer code SVRegSP002

26 Working with Smart Vision Europe Ltd As a premier partner we sell the IBM SPSS suite of software to you directly We re agile, responsive and generally easier to deal with As experts in SPSS / analytics / predictive analytics we will Deliver classroom training courses Offer side by side training support Offer skills transfer consulting Run booster and refresher sessions to get more from your SPSS licences Give no strings attached advice We are a support providing partner so if you already have SPSS you can source your technical support directly from us (identical costs to IBM) We offer telephone support with real people as well as web tickets / queries We offer how to support to help you get moving on your project quickly

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