Ch. 2 Research Methods
Terms… pg Scientific method Empirical investigation Theory Independent variable Dependent variable Data Confounding / Extraneous variables Controls Random assignment Correlational study Survey Naturalistic observation Longitudinal study Cross-section study Cohort–sequential Personal bias Expectancy bias Double-blind
How do you know G. Washington was the 1 st president of the U.S.? How do you know that you really have a stomach? Why have humans throughout the ages believed in a god or gods? What makes you so sure the sun will rise tomorrow? How do you know the color of my shirt? How can you be sure that there aren’t little creatures inside computers? Are you sure you don’t have a big hole in the back of your pants or skirt? Authority Intuition Reason (deductive / inductive) Observation
How Do Psychologists Develop New Knowledge? scientific method to test ideas empirically
empirical investigation – sensory experience & observation as research data Developing New Knowledge scientific method – 5-step process for (e) investigation of hypothesis control biases & subjective judgments The Amazing Randi--Skeptic
5-Steps of Scientific Method… Develop hypothesis Perform controlled test Gathering objective data Analyzing results Publish, criticize, & replicate results
Developing a hypothesis Hypothesis – statement predicting outcome Operational definitions – exact procedures.. 1- establishing experimental conditions 2- measurement of results 5-Steps of Scientific Method i.e. intelligence = measured by IQ test **precise definition of characteristic **how data collectors are to measure characteristic **way to get a # from one of your variables
Perform controlled test Independent variable – manipulated by experimenter 5-Steps of Scientific Method Cause (what you are studying)
Gathering objective data Data – Info gathered by researcher & used to test hypothesis Dependent variable – measured outcome; responses of participants 5-Steps of Scientific Method Effect (result of experiment)
Analyze results statistical analysis: hypothesis - accepted or rejected 5-Steps of Scientific Method
Publish, criticize, & replicate results 5-Steps of Scientific Method work w/stand scientific scrutiny
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Types of Psychological Research Methods: Experiments & Non-experimental Experiments- researcher controls “all” conditions & directly manipulates conditions {A B} 1 st – basic inquiry 2 nd – establish variables 3 rd – ensure controls (except IV) EExperimental grp- CControl grp- 4 th – select subjects
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Be curious! 1.Does involvement in HS athletics improve academic performance? 2.Does excessive texting impede face-to-face relationships? 3.Does personality influence musical preferences? 4.Do ads portraying unrealistic body types reduce the self-image of the viewer? 5.Does student consumption of caffeine in the morning improve first period grades?
Copyright © Allyn & Bacon 2007 Pick a question… apply descriptive research techniques to research
Types of Psychological Research Non-experimental methods: Correlational studies Surveys Naturalistic observation Longitudinal studies Cross-sectional studies Cohort-sequential studies
Non-Experimental Methods Correlational studies relationship b/w variables ccausation? CC = (r) *0 =*+ =* - =
Correlation & Strength
University of Virginia school of Engineering (n=588)
Start w/ 2 Dependent Variables 1.DV = Height DV = Weight 2.DV = Golf Score DV = Number of years the person has played golf 3.DV = IQ scores DV = Size of your big toe 4.DV = Salary DV = Happiness
Do variables vary together? Are the numbers which represent height somehow related to (vary with) the numbers which represent weight? Does a person’s golf score vary w/ yrs of practice? Does IQ vary w/ big toe length? Does happiness vary w/ salary?
Operational Definitions in green 1.DV = Height (inches w/o shoes) DV = Weight (lbs w/o clothes) 2.DV = Golf Score (on golf course x) DV = Number of years the person has played golf 3.DV = IQ scores (WAIS test) DV = Size of your big toe (in mm from top of joint to top of toe) 4.DV = Salary (annual salary including bonuses & benefits) DV = Happiness (???)
or Correlation is NOT Causation
Non-Experimental Methods Description- gathering evidence about A & B Survey social desirability effect Naturalistic Observation reactivity-
Non-Experimental Methods
Cohort-sequential – $pending habit$ –cohort effect- differences b/w grps growing up in different time periods
Experimentation
Comparison Research Method AdvantagesLimitations Naturalistic Observation More accurate than reports after the fact Behavior is more natural Observer can alter behavior Observer Bias Not generalizable Case Studies Depth Takes advantage of circumstances that can not be replicated Can’t generalize Time consuming & expensive Observational Bias Surveys Immense amount of data Quick & inexpensive Generalize Replicable Poor sampling- skew results Wording Effect Social Desirability Bias
Sources of Bias personal- –Hawthorne Effect- single blind –expectancy- (experimenter) ** confirmation
–double-blind- subjects & experimenter sampling bias- sample NOT representative of population placebo effect- participants’ expectations >>>experience some change (treatment)
Sources of Bias distortions in self-report- –social desirability bias- socially approved extraneous or confounding- any variable other than IV likely to influence DV (specific study) variables linked & difficult to sort out specific effects subject experiment situational
APA’s Guidelines 1)participation – voluntary / informed consent [w/d any time] 2) no exposure to dangerous research procedures (psychological & physical) 3) deception = must “debrief” 4) right to privacy 5) pain or harm to animals --- justified 6) approval from institution & IRB / report fully
Ethics in Research Deception “Good Samaritan” Debriefing informed ASAP Animal Studies living conditions discomfort v value (federal law ‘85)
Making Sense of Data? Statistics --- major purposes: (1) descriptively to characterize measurements (2) inferentially judge (measurements) result of chance
Organizing Data & Stats 1 st results >>> frequency distribution convert data = histogram Descriptive Statistics measures of central tendency… mmean- mmedian- mmode- range- Sales Position--- $20,000 $25,000 $35,000 $200,000
Statistical Reasoning Skewed Distribution Mode Median Mean One Family Income per family in thousands of dollars
Descriptive Statistics standard deviation- most widely used * lrg # = * sm # =
normal distribution Descriptive Statistics
Correlation CCorrelation Coefficient sstatistical measure of extent to which two factors vary together, & how well either factor predicts the other Correlation coefficient Indicates relationship (+ or -) Indicates strength of relationship (0 to 1) r = +.37
Correlation Perfect positive correlation (+1.00) No relationship (0.00)Perfect negative correlation (-1.00) Scatterplots, showing patterns of correlations
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Bias??? –77% of New Yorkers were interested in plants and trees, but only 39% were interested in botany –48% where interested in fossils, but only 39% where interested in paleontology –42% where interested in rocks and minerals, but 53% where interested in Geology
Bias??? –Do you favor an amendment prohibiting abortions? –Do you favor an amendment protecting the life of an unborn child?
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Survey Wording can change the results of a survey. Q: Should cigarette ads and pornography be allowed on television? (not allowed vs. forbid) Wording Effect
Correlations: A relationship between Two Variables Correlation– A relationship between two variables, in which changes in one variable are reflected in changes in the other variable Correlation coefficient– A number between -1 and +1 expressing the degree of relationship between two variables
Copyright © Allyn & Bacon 2007 Class Survey Write down whether you agree or disagree with the following statements 1.There is too much concern in the courts for the rights of criminals 2.The death penalty should be abolished 3.Wealthy people should pay a larger share of taxes then they do now 4.Federal military spending should be increased
Making Inferences w/ inferential statistics Inferential statistics- used to assess whether results of a study are reliable or whether they might be simply result of chance Sampling Random sample- each member (population) has equal chance of inclusion into a sample (unbiased) If survey sample is biased, its results are questionable Representative sample Statistical significance
Standard Deviation
Does Misery Love Company?
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Journal Question… Greatest Inventions of the Past 2,000 Years David Myers – control group “Others in this scientific-minded group have appropriately mentioned the scientific method. Speaking for my discipline, let me sharpen this. When it comes to thinking smart – to sifting reality from wishful thinking – one of the great all-time inventions is the control group.” ** Why is the control group so vital to psychology, the sciences, and everyday life? (example)
Copyright © Allyn & Bacon 2007 Questions Science Cannot Answer The scientific method is not appropriate for answering questions that cannot be put to an objective, empirical test Ethics Morality Religious beliefs Preferences
Comparison Research MethodAdvantagesLimitations Naturalistic Observation More accurate than reports after the fact Behavior is more natural Observer can alter behavior Observational Bias Cannot be generalized Case Studies Depth Takes advantage of circumstances that could not be coordinated in an experiment Not representative Time consuming and expensive Observational Bias Surveys Immense amount of data Quick and inexpensive Sampling biases can skew results Bad Questions can corrupt data Accuracy depends on the ability and willingness of the participants.
Assigning participants to experimental (Breast-fed) and control (formula-fed) conditions by random assignment minimizes pre-existing differences between the two groups. Clinical Research cont’d Random Assignment 13 This is not the same as random selection!
Breast milk makes babies smarter! A summary of steps during experimentation.
6.Does gamification of the classroom improve/increase student engagement? 7.Does a community service requirement positively or negatively impact student opinions of community service? 8.Does HR increase communication in a large suburban HS? 9.Do teacher websites improve student performance in class? 10.Does focus on minor rules (flip-flops and hats) reduce student adherence to major rules (insubordination or class cutting) ? Be curious!
What is true about the scatter plot… A- no relationship apparent B- positive relationship displayed C- r = -.35 D- r = 6 E- inverse relationship