Extension: How/why might correlations be used in psychology? Discuss with somebody else what you can remember about correlations from GCSE maths.

* Correlations

By the end of this lesson you will be able: * To describe what is meant by the following: Correlation, positive correlation, negative correlation, zero correlation, correlation coefficient * To explain the difference between experiments and correlations. * To apply those terms to research examples. * To evaluate the use of this method.

*C*C orrelations Correlation is shown graphically and in a numerical representation (correlation coefficient) Correlation is a technique that measures whether or not there is a relationship between two variables (known as co variables). Can be a method in its own right OR can be used to analyse data gathered from another method. You DO NOT need to take notes.

* Correlation Coefficients * They can be represented mathematically as a correlation coefficient * This is a number between +1 and -1 and is represented by the letter r Correlation coefficients range from -1_______________________________0_____________________________ +1 A perfect negativeno correlation A perfect positivecorrelation

* Positive (+) correlation  This means that as one variable increases the value of the other variable will also increase. E.g. the MORE TIME spent studying the HIGHER your exam result  As one goes up, so does the other. Anything measured above 0 on the correlation coefficient becomes a positive correlation. r = +0.2 would be a weak positive correlation. r = +0.9 would be a strong positive correlation.

* Scattergram 1)What are the two variables that we are looking at in this study? 2)What would you guess is the correlation coefficient? 3) Look at the participant who scored the highest for confidence, what can we say about their number of friends?

* Negative (-) correlation  This means that as one variable increases the other variable being measured decreases. E.g. the MORE time socialising with friends, the LESS revision gets done for your exam.  One goes up, the other goes down. Anything measured below 0 on the correlation coefficient becomes a negative correlation. r = -0.2 would be a weak negative correlation. r = -0.9 would be a strong negative correlation.

* Scattergram 1) What are the two variables that we are looking at in this study? 2) What would you guess is the correlation coefficient? 3)What does the scatter diagram tell us about the fittest people?

* Zero (o) correlation * This means that the two variables are not related at all. * E.g. The EARNINGS of a deep-sea fisherman and the SIZE of a portion of chips. Zero correlation shows no relationship between the two variables. Anything measured close to 0 on the correlation coefficient shows zero correlation. r = would show zero correlation. r = would show zero correlation.

* Scattergram 1) What are the two variables that we are looking at in this study? 2) What would you guess is the correlation coefficient? 3) What does the scatter diagram tell us about the relationship between shoe size and intelligence?

* Check your understanding 1.The more aggressive parents are, the more aggressive their children tend to be. 2.The hotter the weather, the fewer clothes people wear. 3.The more expensive the petrol, the less petrol people buy. 4.The hotter the weather, the more clothes people remove. 5.The fewer sweets eaten, the fewer fillings needed. Identify the relationship.

* Check your understanding 1. r = r = r = r = r = 0 Mini whiteboard time! For each of the following decide: 1)Is it showing a positive, negative or zero correlation. 2)How strong is the correlation. Now complete the activity on correlations in your activity booklet (pages 7-9).

* The significance of the correlation WATCH OUT!! * Significant correlations simply indicate there IS a relationship NOT why or how * Correlation does NOT mean one variable caused the other to change There are 3 possible explanations: 1. Causality (one variable caused the other to change). 2. Chance (variables just happened to be related). 3. Third factor involved (another variable is causing the relationship).

* 3. Third factor (example) * What else may be linked to the ice cream sales that could explain this positive correlation? * In this case the causal variable is obviously temperature (e.g. the third factor). * For example, there is a relationship between the colour of grass and ice-cream sales. The more yellow the grass gets the more ice cream is sold.

* Correlations vs experiments Discuss: 1)What are the key differences between experiments and correlations? 2)What are the potential strengths and limitations of correlations? Extension: Do the strengths outweigh the weaknesses? Consolidate your knowledge by reading the information on correlations in your booklet and completing the activity on page 10 of your activity booklet.

You are now able: * To describe what is meant by the following: Correlation, positive correlation, negative correlation, zero correlation, correlation coefficient * To explain the difference between experiments and correlations. * To apply those terms to research examples. * To evaluate the use of this method.

* Homework Deadline given last lesson: Work on Assessment one. Preparation for next lesson: Consider the most effective way to find participants for your research.