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Psychological Research Methods & Statistics Excavating Human Behaviors Psychology & Research Methods A “Scientific Attitude” is critical… Curiosity – a passion to explore and understand. Skepticism – psychologists, like other scientists, approach the world of behavior with curious doubt. The are constantly asking two questions: What does it mean? How do you know? Humility – an awareness and acceptance that we may have to reject our own ideas or theories (if they are proven wrong). Critical Thinking – a scientific approach prepares/demands us to think “smarter” to examine assumptions, evaluate evidence, and assess conclusions. Hindsight Bias The tendency to believe, after learning the outcome, that you knew it all along. With 20/20 hindsight, everything seems obvious. After the Chris Brown / Rihanna incident….my husband said he knew Chris Brown was a violent kid!!! Did he really? Overconfidence We tend to think we know more than we do. We tend to be more confident than correct! 82% of U.S. drivers consider themselves to be in the top 30% of their group in terms of safety 81% of new business owners felt they had an excellent chance of their businesses succeeding. When asked about the success of their peers, the answer was only 39%. (Now that's overconfidence!!!) Exercise: Unscramble these Anagrams WREAT ETRYN GRABE Anagram Solutions WREAT --- WATER ETRYN --- ENTRY GRABE --- BARGE The Barnum Effect It is the tendency for people to accept very general or vague characterizations of themselves and take them to be accurate. Barnum Effect Experiment - Subjects take a bogus personality test that produces a set of vague and even self-contradictory statements such as "you can be outgoing at times but at times you can also be shy." When put in the correct context people will say that this analysis captures them to a "T." “There’s a sucker born every minute.” P.T. Barnum Applied versus Basic Research Applied Research has clear, practical applications. YOU CAN USE IT!!! Basic Research explores questions that you may be curious about, but not intended to be immediately used. Studying how kissing changes when you get older is interesting…but that’s about it. Research on therapies for drug addicts has a clear purpose. Psychological Research Methods Psychology is an experimental science. Assumptions must be supported by evidence. Psychologists use a variety of research methods to study behavior and mental processes. Psychologists follow the same general procedure when conducting research: 1. 2. 3. 4. 5. 6. Asking research questions Forming hypothesis (hypotheses) Testing the hypotheses Analyzing the data (results) And drawing conclusions Eventually, replicating research The Scientific Method Step 1: Forming research questions – Beginning with scientific curiosity and interest, many research questions come from daily experience, psychological theory, or common knowledge. Step 2: Forming hypotheses – A hypothesis is a predicted “answer” the question (or in other words, “an educated guess”). The Scientific Method Step 3: Testing hypotheses – 1. Once a hypothesis has been formed, it must be scientifically tested and proved right or wrong. 2. This part of conducting research is the “actual” experiment. 3. Psychologists use a variety of methods to test hypotheses. Step 4: Analyzing Results – 1. Data is analyzed using statistics 2. The more data collected, the more complex a task it is to analyze. The Scientific Method • Step 5: Drawing Conclusions – • Once the results have analyzed, a psychologists can draw or make conclusions about his/her questions and hypotheses. • Step 6: Replication – 1. Even when a research study carefully follows proper procedures, its findings might just represent a random occurrence. 2. To confirm the results and conclusions of a research study, the study must be replicated. 3. The study must be repeated and it must produce the same or similar results as before. 4. If there are different results, then the findings of the first study are questioned. Research Methods Terminology Hypothesis Expresses a relationship between two variables. A variable is anything that can vary among participants in a study. Participating in class leads to better grades than not participating. Independent Variable Whatever is being manipulated in the experiment. Hopefully the independent variable brings about change. If there is a drug in an experiment, the drug is almost always the independent variable. Dependent Variable The dependent variable would be the effect of the drug. Whatever is being measured in the experiment It is dependent on the independent variable. Operational Definitions Explain what you mean in your hypothesis. How will the variables be measured in “real life” terms. How you operationalize the variables will tell us if the study is valid and reliable. Let’s say your hypothesis is that chocolate causes violent behavior. What do you mean by chocolate? What do you mean by violent behavior? Selecting Subjects Population – all members of a given group (of study) Sample – a subset of the population which is representative of the whole population Random Sample – a sample in which every member of the population has an equal change of being selected Stratified Sample – a sample in which each subgroup of the population is represented proportionally to its size in the population Key Research Terminology Using a random sample that represents the whole population, a researcher can generalize findings to the entire population. CAUTION: Overgeneralization – is the making of generalizations using unrepresentative cases. It is easy to do but typically erroneous. False Consensus Effect: the tendency to overestimate the extent to which others share our beliefs and behaviors Methods of Collecting Data Survey – commonly used in both descriptive and correlational studies, questionnaire method sampling many cases (individuals) in less depth Case Study – the study of one or more individuals in great depth, to inform about an entire population or sample Testing – psychological tests are given to measure certain mental processes, such as intelligence, aptitude, or personality The ideal case study is John and Kate. Really interesting, but what does it tell us about families in general? The Survey Method Used in both descriptional and correlational research. Use Interview, mail, phone, internet etc… The Good- cheap, anonymous, diverse population, and easy to get random sampling (a sampling that represents your population you want to study) Survey Method: The Bad Low Response Rate People Lie or just misinterpret themselves. Wording Effects How accurate would a survey be about the frequency of diarrhea? Naturalistic Observation Observing and recording behaviors of an organism in natural environment No control- just an observer (do not manipulate the environment) This method does not explain behavior but describes it What are the benefits and detriments of Naturalistic Observation? Methods of Collecting Data Laboratory Observation – this research method involves watching and recording behaviors of organisms NOT in their natural environment BUT in a laboratory setting. Cross-sectional Studies – uses participants (subjects) of different ages to compare how certain variables may change over the life span. Longitudinal Studies – use one group of participants over a long period of time. This method of study tracks the change over time of the participants. Correlational Research Detects relationships between variables Does NOT say that one variable causes another There is a positive correlation between ice cream and murder rates. As more ice cream is eaten, more people are murdered. Does that mean that ice cream causes murder? Types of Correlation Positive Correlation The variables go in the SAME direction. Negative Correlation The variables go in opposite directions. Studying and grades hopefully has a positive correlation. Heroin use and grades probably has a negative correlation. Correlation vs. Cause & Effect Correlation coefficient is a statistical measure of relationship (it reveals how closely related two factors are or how closely two factors vary together and thus how well either one predicts the other). Positive and negative correlations are possible A relationship does not mean causation!!! • For example, watching TV violence positively correlates with aggressive behavior; but does not necessarily mean watching violence on TV causes aggressive behavior. Correlation Coefficient A number that measures the strength of a relationship. Range is from -1 to +1 The relationship gets weaker the closer you get to zero. Which is a stronger correlation? -.13 or +.38 -.72 or +.59 -.91 or +.04 How to Read a Correlation Coefficient Experimental Method Looking to prove causal relationships Cause = Effect Laboratory v. Field Experiments Eating too many bananas causes Smoking causes health issues. Constipation Experimental Research In an experiment, participants receive what is called a treatment, such as a change in room temperature or a new drug. Then, psychologists carefully observe the participants to determine how the treatment influences their behavior. Independent and Dependent Variables All research studies measure and observe variables (factors), especially experimental studies. In an experiment, the independent variable is the factor that the researcher manipulates (controls) so that they can determine its effect on the dependent variable. The dependent variable is the factor that depends on the manipulated independent variable(s). Experimental and Control Groups The experimental group is a group of participants who receive the treatment or manipulated variable. The control group is a group of participants who do not receive the manipulated variable (instead a placebo of sorts). All other variables/factors are held constant (or equal) for both groups (to try to isolate a cause and effect relationship between independent variable(s) of interest to the research psychologist and the dependent variable. If the research psychologist fails to manage the ‘other’ variables (or hold them constant), they become confounding variables. Confounding variables are baaaaad!!! Beware of Confounding Variables If I wanted to prove that smoking causes heart issues, what are some confounding variables? The object of an experiment is to prove that A causes B. A confounding variable is anything that could cause change in B, that is not A. Lifestyle and family history may also effect the heart. Experimental Method continued Psychologists randomly place participants (subjects) into one group or another. – EXAMPLE: The effect of extracurricular activities on student’s academic success. Once subjects are randomly placed into the control and experimental groups, the researcher makes sure that all other variables are the same for all students regardless of group. Using this grouping method in the experimental method is called a controlled experiment. The Placebo Effect In research studies and in our daily lives, our expectations affect what happens to us. Feeling better simply because we expect to feel better and for no other reason is an example of the placebo effect. A placebo is a substance or treatment that has no effect apart from the person’s belief in it. Experimental Method continued Single-blind vs. Double-blind Studies In a single-blind study, participants do not know whether they are receiving the treatment (the manipulated independent variable) or not. In other words, they do not know if they are in the experimental group or in the control group. This process avoids the placebo effect. In a double-blind study, both participants and researchers are unaware of who has placed in which group. Descriptive Statistics Just describes sets of data. You might create a frequency distribution. Frequency polygons or histograms. Measure of Central Tendency Mean, Median and Mode. Watch out for extreme scores or outliers. Let’s look at the salaries of the employees at Dunder Mifflen Paper in Scranton: $25,000-Pam $25,000- Kevin $25,000- Angela $100,000- Andy $100,000- Dwight $200,000- Jim $300,000- Michael The median salary looks good at $100,000. The mean salary also looks good at about $110,000. But the mode salary is only $25,000. Maybe not the best place to work. Then again living in Scranton is kind of cheap. Normal Distribution In a normal distribution, the mean, median and mode are all the same. The mean is the most commonly used measure of central tendency, but its accuracy can be distorted by extreme scores or outliers. Distributions Outliers skew distributions If group has one high score, the curve has a positive skew (contains more low scores) If a group has a low outlier, the curve has a negative skew (contains more high scores) Other measures of variability Range: distance from highest to lowest scores. Standard Deviation: the variance of scores around the mean. The higher the variance or SD, the more spread out the distribution is. Do scientists want a big or small SD? Shaq and Kobe may both score 30 ppg (same mean). But their SDs are very different. Scores A unit that measures the distance of one score from the mean. A positive z score means a number above the mean. A negative z score means a number below the mean. Normal Distribution Inferential Statistics The purpose is to discover whether the finding can be applied to the larger population from which the sample was collected. T-tests, ANOVA or MANOVA P-value= .05 for statistical significance. 5% likely the results are due to chance. Statistics & Research Methods Null hypothesis: (H0) is a hypothesis (scenario) set up to be nullified, refuted, or rejected ('disproved' statistically) in order to support an alternative hypothesis Type I error: the error of rejecting a null hypothesis when it is actually true Type II error: the error of failing to reject a null hypothesis when the alternative hypothesis is the true state of nature T-test The t-test assesses whether the means of two groups are statistically different from each other. This analysis is appropriate whenever you want to compare the means of two groups www.graphpad.com/quickcalcs/ttest1.cfm X = mean of group Var = Standard deviation of group N = number in sample Research & Statistics Assignment 1 Gather shoe size data from 10 females and 10 males, recording the shoe size of each. Then calculate the measures of central tendency (mean, mode, median) and graph the data set in a frequency histogram and box-plot. Find and discuss any outliers Explain the gender difference, if one exists. Research & Statistics Assignment 2 Using the Research Question: How many pairs of shoes do males and females own? Write a testable hypothesis. Next, gather data from 10 females and 10 males, recording the number of shoes owned by each. Ask your participants, “How many pairs of shoes do you own?” and (obviously) record their answer and gender. Calculate the measures of central tendency and standard deviation and test for differences between means using a t-test. (use www.graphpad.com/quickcalcs/ttest1.cfm to help you calculate a t-score) Write a brief conclusion about your results (at least 1 paragraph). Make sure you give an explanation for the APA Ethical Guidelines for Research IRB- Internal Review Board Both for humans and animals Animal Research Clear purpose Treated in a humane way Acquire animals legally Least amount of suffering possible. Human Research No Coercion- must be voluntary Informed consent Anonymity No significant risk Must debrief