1. Trying an Experiment BATs Conduct a memory experiment with real participants in a professional and ethical way Collect data Have you got all your materials ready? We will be testing year 11 students period 1 After we have collected the data we will analyse it back in HU7 or the Bath Spa room.

2. Descriptive Statistics BATs  Use measures of central tendency (mode, median and mean)  Analyse the advantages and disadvantages of each type of descriptive statistics.  Draw graphs and interpret data from real experiments

3. Descriptive Statistics  Measure of central tendency  Gives a typical value for the data set  Tells you where the middle of the data set is  Measure of dispersion  Indicates how the data are spread out  Tells you what the rest of the data are doing www.psychlotron.org.uk

4. Descriptive Statistics  The aim of descriptive statistics is to give an accurate summary of the data  The wrong choice of statistic gives a distorted picture of the data  This can lead to the wrong conclusions being drawn from the data  Each measure of CT and D has its advantages and disadvantages www.psychlotron.org.uk

5. Measures of Central Tendency  The mean  Adv: it uses all the values in the set, so is most sensitive to variations in the data  Dis: it can be artificially raised or lowered by an extreme value, or by skewed data  Use it when the data are normally distributed, unskewed and there are no outliers www.psychlotron.org.uk

6. Measures of Central Tendency  The median  Adv: it is based on the order of the data, not their actual values, so not distorted by extreme values  Dis: however, this makes it less sensitive to variations in the data  Use it when you can’t use the mean because of skew, outliers etc. www.psychlotron.org.uk

7. Measures of Central Tendency  The mode  Adv: it’s the only measure suitable for summarising category/frequency data  Dis: for many data sets there is no modal value, or their may be several  Use when dealing with frequency data, and/or where there is a clear modal value in the set www.psychlotron.org.uk

8. Which stats would you choose?  In groups of 3 read the ‘Choice of Statistics worksheet  Discuss q 1 and 2 – which measure of central tendency would be best for each list of data? 1. Should have chosen the colour that was picked most often – the mode a.Mean, b. mode, c. mean or median ( numbers in order), d. mode, e. Median (mean not best because a few outliers)

9. Measures of Dispersion   Range:   Simple measure of dispersion- shows the total spread of data.   Difference between highest and lowest scores in a set of data: top value minus bottom value plus 1.   Affected by atypical, extreme values.   Interquartile ranges can also be used see p 119 Exploring Psychology

10. Measures of Dispersion   Standard Deviation:   Measure of dispersion- shows degree of clustering of values around the mean.   Calculating standard deviation (S): Square root of sum of all squared deviations from the mean, divided by N (or sometimes N- 1).   The smaller the sd the closer the scores are to the mean, high sd = scores spread out a long way from mean.

11. Measures of Dispersion   Standard Deviation:   The most accurate measure of dispersion –   It is more precise than range because all values are taken into account   BUT … have to calculate it – time consuming

12. Displaying Data  Tables – clear headings with units of measurement  Graphs – see findings at a glance  Bar chart – discrete categories, bars separated  Histogram – x axis has continuous data, no gaps between bars (DV on x axis, frequency on y axis)  Line graph/frequency distribution curve e.g Yerkes- Dodson curve

13. What type of graph? What types of graph are used in each of the following…  Murdock (1962) p16  Van Ijzendoorn and Kroonenburg (88) p57/8 Frequency distribution curve Bar chart

14. Plenary  Answer the questions 1, 4,5,6 and 7  Use the answer sheet to mark your answers

15. Using your own data BAT Draw graphs and interpret data from your own experiment Evaluate the work of others

16. Over to you  Select the most appropriate descriptive stats for your data (central tendency and dispersion) and calculate  Display your data in a graph of your choice  What does your data tell you?  Will you accept or reject your hypothesis?  How could you improve your method?

17. Peer Review  Before a piece of Psychological research can be accepted it is reviewed by other psychologists to check the work’s validity and reliability.  Read the method, and data analysis of someone in a different group.  Would you accept their work?  How could reliability and/or validity be improved

18. Plenary and Homework  Homework – complete the worksheet by next lesson  Start to Revise for Mock exam – use the blog quiz!! The results will be emailed to me