© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Lecture # 2 Measuring behaviour and scientific methodology

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology 1.The Scientific Method in Psychology …measurement correlation, testimonials cause and effect statistics 2.Ethics 3.Understanding Research Results more statistics

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology The Scientific Method in Psychology  Identifying the problem  Designing an experiment  Performing an experiment  Correlational studies  Generality

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Identifying the Problem  What question do you want to study?  Go to the library and find out what other people have found.  Psychlit© is a good place to start.  Hypotheses vs. Theories  An hypothesis is a statement of what you think should happen in your experiment.  A theory is a set of statements designed to explain a set of results and is more encompassing than an hypothesis.

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Designing an Correlational Experiment  Observation how do “things” seem to interact.  Form an hypothesis  Gather the information (measurables)  Interpret the data  Hypothesis appears to be correct/incorrect  Modify Hypothesis?????

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Correlational Studies F 2.7  There is an excellent correlation between the cancer rate of the population and the number of telephone poles that are currently in use.  The cancer rate positively correlated to smoking.  Why is statement one (apparently) ridiculous and the second one is not? Correlation does not equal cause and effect

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Designing an Experiment  Observation: People prefer to wear different colours of clothing. What does this indicate???  Go to the library: => What do others know?  Form your hypothesis:  “People who wear red will add three numbers together faster than people who wear green.”

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Independent and Dependent Variables F 2.2  Experimenter sets independent variable in this case “colour”  Experimentor then measures (perceived) dependent variable. Ie the time to add three numbers.  The data is then compiled…  So lets do it!

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology The Procedure F 2.3  1. Pick students wearing red from class  2. Pick students wearing green  3. Ask question X + Y +Z = ?  4. Compile data.

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology The Results of our Experiment  Red  Person 1: 1.72 s  Person 2: 1.65 s  Person 3: 3.00 s  Person 4: 1.90 s  Person 5: 2.20 s  Person 6: 2.55 s  Person 7: 2.46 s  Total: s  Average (Total/7): 2.21 s  Green  Person 1: 3.13 s  Person 2: 2.67 s  Person 3: 3.90 s  Person 4: 3.90 s  Person 5: 1.25 s  Person 6: 4.32 s  Person 7: 1.63 s  Total: s  Average (Total/7): 2.97 s The Average Response

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology The Results of our Experiment  Person 1: 1.72 – 2.21 =  Person 2: 1.65 – 2.21 =  Person 3: 3.00 – 2.21 = 0.79  Person 4: 1.90 – 2.21 =  Person 5: 2.20 – 2.21 = 0.01  Person 6: 2.55 – 2.21 = 0.34  Person 7: 2.46 – 2.21 = 0.25 Total variability 0 (approx) The Variability of the Red Responses

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology The Results of our Experiment  Person 1: (-0.49) 2 = 0.24  Person 2: (-0.56) 2 = 0.31  Person 3: 0.79 (0.79) 2 = 0.62  Person 4: (-0.31) 2 = 0.10  Person 5: 0.01 (0.01) 2 =  Person 6: 0.34 (0.34) 2 = 0.12  Person 7: 0.25 (0.25) 2 = 0.06 Total (variability) 2 = 1.45 We then divide by the the number of observations (7) to get the average variability or variance = 0.21 Taking the square root of this gives 0.46 This number is called the standard deviation The Variability of the Red Responses

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology So the response of the red group was on average 2.21 but the responses of the group varied by about 0.46 seconds So lets look at the green responses……

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology  Person 1: 3.13 – 2.97 = 0.16s  (0.16) 2 = 0.03  Person 2: 2.67 – 2.97 = -0.30s  (0.30) 2 = 0.09  Person 3: 3.90 –2.97 = 0.93s  (0.30) 2 = 0.09  Person 4: 3.90 –2.97 = 0.93s  (0.93) 2 = 0.86  Person 5: 1.25 –2.97 = -1.72s  (–1.72) 2 = 2.96  Person 6: 4.32 –2.97 = 1.35s  (1.35) 2 = 1.82  Person 7: 1.63 – 2.97 = -1.34s  (1.34) 2 = 1.80 Sum of the squared variability 7.65 Therefore the group variability (variance) is 1.09 and the standard deviation is then 1.05 The Results of our Experiment Chapter 2

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology So the response of the green group was on average 2.97s but the responses of the group varied by about 1.05s To Summarise our results then we can say: Red 2.21 ± 0.46 s Green 2.97 ±1.05s

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Are these Responses Different from one another ? Only a proper statistical test can say but in this case because the responses were highly variable, it is unlikely that the averages reflect a real difference between the groups (ie the difference 2.21s versus 2.97s likely occurred just by chance) 2.21 ± 0.46 s 2.97 ± 1.05 s

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Are these Responses Different from one another ? 2.21 ± 0.46 s 5.6 ± 1.05 s Only a proper statistical test can say but in this case because the blue responses are very different on average with little overlap the distributions then it is highly likely that these two responses are different (ie the difference 2.21s versus 5.6s likely did not occur by chance)

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology The Results  Hypothesis is true?  Interpretation why is it true or false  Students who wear red are more extroverted and therefore they perform better under pressure.

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Understanding Research Results 1. Descriptive statistics  What are the results?  Use the mean, median range and variance 2. Inferential statistics  Are the results significant?  Use mathematical comparisons to decide if two or more populations have different means, medians etc.

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Inferential Statistics: Are the Results Significant?  Statistical significance: the likelihood that an observed relation or difference between two variables is not due to chance  Statistical analyses: the way in which we determine statistical significance  Correlation coefficient  Inferential statistics

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Generality  What does your experiment mean in the real world?  Generalization: Can you apply your results to the population from which you took your sample?

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Confounding of Variables  We must control our independent variables.  Is the person only wearing red ? Are other colours involved?  An inadvertent alteration of more than one variable during an experiment is called a confound. The numbers were not presented in the same order or was the fashion in which they were read or spoken different? F 2.4

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Counterbalancing  In the previous experiment, the order of the stimuli was always the same, and may have confounded our results.  Counterbalancing the order of the stimuli prevents confounding. F

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Performing an Experiment  Reliability of Measurements  The repeatability of a measurement or:  Will you get the same result twice? Will I get the same result independent of sex or age? Is colour the only determinant?  Selecting the participants  Who will be in your study?  Will this have an effect on your results?

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Another type of experiment  Control  Never listen to music but are instead left in room that is silent  Test  Listen to “Whoops I did it again” for one hour without interuption. Hypothesis; Listening to Britney Spears makes people dance more frequently at discothèques than those who don’t listen to her music. Measure time on dance floor

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Participant’s Expectations F 2.6 Traumatised by never ending musical stimulus “Happy” about their “quiet time” Some dance and some drink heavily Some dance and none drink heavily

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Getting it right  But lets suppose that the experimenter gets it right and reduces the amount of time listening so that the subjects are not annoyed  How do you (imply) show cause and effect  Vary the time of listening versus dance  i.e. determine a causal relationship

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Descriptive statistics: What are the Results?  Descriptive statistics  Graphing the data  Linear relationships  Non-linear relationships

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology A Linear Relationship Time spent listening Time on dance floor (hrs)

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Scatterplots of Different Correlations F 2.9

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Time spent listening Time on dance floor (hrs) A Non linear relationship

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Correlational vs. Experimental Studies  Correlational studies:  cannot infer causation  can only state that there is a relationship between the variables of interest  may be due to a third unknown variable  Experimental studies:  can infer a causal relationship between the two variables of interest  may be due to a third unknown variable!

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Ethics 1.Research with human participants 2.Research with animals

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Research with Human Participants  Requires compliance with the following principles: 1.Informed consent 2.Confidentiality 3.Minimal risk 4.Debriefing

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Research with Animals  As animals cannot give informed consent, we must comply with the following principles: 1.Is this an important research topic? 2.Have we minimized harm to the animal? 3.Are the animals receiving the best possible care? 4.Are the animals being treated humanely?

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Inferential Statistics: Frequency Distributions F 2.11 Number of occurances Response time (s) N =1000 mean

© 2000 Pearson Education Canada Inc., Toronto, Ontario The Ways and Means of Psychology Running an Experiment  Controls  Naïve controls: no treatment of any kind  Placebo Controls: the subject does not if they are being treated  Double Blind Controls: Neither experimenter nor the the subject are aware of the treatment  Sham Controls: an invasive procedure is performed without a treatment