7/24/03 1 Psychological Research Methods: A Search for Laws Basic assumption: events are governed by some lawful order

Table of Contents 7/24/03 2 I. The Scientific Method: Terminology Research methods: general strategies for conducting scientific studies Operational definitions - definitions used to clarify precisely what is meant by each variable (making it measurable)

Table of Contents 7/24/03 3 terminology con’t Participants (subjects) - organisms whose behavior is systematically observed in a study Data collection techniques - empirical means of observation and measurement Ex: scales of measurement Statistics – mathematical measures used to analyze data and decide whether hypotheses were supported

Table of Contents 7/24/03 4 Basic Research Criteria 1. Objective/systematic measures must be employed to avoid bias 2. Empirical measures must be employed (measures which rely on observation, NOT theory) 3. Findings must be made available to public 4. Findings must be replicable!!!

Table of Contents 7/24/03 5 II. Ethics in Psychological Research Ethical standards for research are set by APA. Goal: Ensure both human and animal subjects are treated with dignity Some Guidelines: Informed consent Participant’s right to withdraw Debriefing Confidentiality of findings The question and justification of deception

Table of Contents 7/24/03 6 The question of animal research – Controversy among psychologists and the public – Reasons for the use of animals Can be studied longer Shorter life span Doesn’t know it’s part of an experiment (no intentional deception) May be used in ways unethical for humans Some bodily processes are similar to those of humans Ethics con’t

Table of Contents News Flash! (A true story) A teacher in Roanoke, IL reported… “Some years ago, I asked my administrator about acquiring a colony of rats for running labs. The eventual answer I got was "no" because --get this--my classroom was deemed an unhealthy environment for the rats: inadequate ventilation, excessive heat, and no running water. Apparently, my classroom was perfectly adequate for students and for me, but not for a colony of rats. Only in education!” Psy forum 2008

Table of Contents 7/24/03 8 III. Basic Research Methods A. Experimental Research: Looking for Causes Experiment - research technique in which one variable is manipulated under controlled conditions so resulting changes in another variable can be observed/measured

Table of Contents 7/24/ Hypotheses Hypothesis (H) – a tentative statement about the relationship between two variables Null Hypothesis (H o ) – the assertion that the independent variable will have NO effect on the dependent variable * There is no true relationship between the observed variables

Table of Contents 7/24/ Variables All experiments have at least two! Independent variable (IV) = variable manipulated/controlled by the experimenter Dependent variable (DV) = variable affected by manipulation, the measured variable

Table of Contents 7/24/ Sampling/Assignment Study participants must represent the intended general population and be selected without pattern. (*This is necessary for ALL types of investigations.) Random sampling procedure – technique used to ensure every member of the population has an equal chance of being selected as a participant Criteria: – 1. Opportunity - equal chance – 2. Independence - selection of one participant cannot affect the selection of another

Table of Contents 7/24/03 12 Stratified Sample – a random sample drawn within restricted categories of a population * Helps ensure the sample represents the intended population - a “representative sample”

Table of Contents 7/24/03 13 Random Assignment – control technique that assigns participants to various groups (experimental & control) in a way that avoids bias (equal opportunity and independence for all)

Table of Contents 7/24/ Experimental and Control Groups Experimental group – participants who receive the independent variable Control group – participants similar to the experimental group, who do not receive the independent variable Placebo group – special type of control group in which the participants receive an inert substance rather than the IV (commonly used in drug testing)

Table of Contents 7/24/03 15 STOP and THINK!!! What is the logic behind the use of different groups?

Table of Contents 7/24/ Experimental Design Variations (Beyond the standard control and experimental groups) Subject Designs – Between-subject design – traditional control/experimental group – Matched pairs – prior to group assignment, the participants are matched on factors known to influence the DV and then are separated into the experimental & control group – Repeated measures (Within-subject design) - expose a single group to various levels of the IV, then average subjects’ performance – Single-subject design – similar to within-subject design, except an average is not used

Table of Contents 7/24/ Additional “Outside” Variables Extraneous variable - a variable, other than the IV, that may influence the DV Confounding variable – any uncontrolled variable that coincides with the IV in such a way that changes in the DV cannot be attributed to the IV alone

Table of Contents 7/24/ Controlling Bias Single-blind technique – control technique in which participants are unaware of their group assignments Double-blind technique – control technique in which participants AND the experimenter are unaware of the participants’ group assignment

Table of Contents 7/24/03 19 and THINK!!! Why would a researcher use a double-blind technique? How does the researcher know who’s getting the IV? STOP Don’t run the stop sign! (Good right hand side info for your notes!)

Table of Contents 7/24/03 20 Strengths and Weaknesses of Experimental Research Strengths – Conclusions about cause-and-effect can be drawn – Allows for control over variables Weaknesses – Artificial nature of experiments – Ethical and practical issues

Table of Contents 7/24/03 21 B. Descriptive/Correlational Methods: Looking for Links Methods used when a researcher cannot manipulate the variables under study Correlational Method Observation (structured or naturalistic) Case studies Surveys Longitudinal studies Cross – sectional studies Cross – cultural studies * Allow researchers to describe patterns of behavior and discover links or associations between variables but cannot imply causation

Table of Contents 7/24/ Correlation: Statistic or Research Method? Correlation - a statistical measure of how two variables are related, represented by the Pearson r – Correlation coefficient (r) is a number between 0 and 1 – Can be positive or negative – The sign indicates HOW the variables are related, the number indicates HOW MUCH they are related – Numbers closer to the absolute value of 1 (whether + or -) indicate stronger relationships

Table of Contents 7/24/03 23 Positive Correlation – as one variable increases/decreases, the other variable increases/decreases in the SAME direction OR the variables move together

Table of Contents 7/24/03 24 Negative Correlation – as the value of one variable increases, the other variable decreases OR the variable move inversely

Table of Contents 7/24/03 25 Note: A correlation of.2 or higher is of practical use, while one below.2 is NOT statistically significant

Table of Contents 7/24/03 26 Strengths and Weaknesses of Correlational research Strengths – Can be used when the experiment is inappropriate or unethical – Can be used in real life situations (no labs) – Stronger/higher correlations allow increased ability to predict one variable based on the other Weaknesses – Does NOT yield a cause and effect relationship – Lacks variable control (third variable problem)

Table of Contents 7/24/03 27 Beware!!! Beware of “Illusory Correlations” the perception of a relationship where none exists.

Table of Contents 7/24/ Observation Structured observation – technique used in a laboratory setting, environment is manipulated Naturalistic Observation – researcher observes without subject awareness and without manipulating the setting

Table of Contents 7/24/03 29 Participant Observation – researcher joins group being studied in an attempt to obtain information known only to group members

Table of Contents 7/24/03 30 Strengths and Weaknesses of Observation ( naturalistic & participant) Strengths – Natural setting – Participants are less likely to change behavior Weaknesses – Lack of control over variables – Participants may alter behavior if researcher is discovered

Table of Contents 7/24/ Case Study An intense, in-depth study of an individual’s past in an effort to solve a current problem or study a psychological phenomenon

Table of Contents 7/24/03 32 Strengths and Weaknesses of the Case Study Strengths – Allows for the study of phenomenon that cannot be ethically reproduced – May reveal more personal information than the survey method Weaknesses – Is not as scientific as other methods due to the lack of control – Due to retrospective nature, it does not prove laws of behavior

Table of Contents 7/24/ Survey The use of questionnaires or interviews to collect information on certain aspects of the participants’ behavior

Table of Contents 7/24/03 34 Strengths and Weakness of the Survey Method Strengths – Allows for rapid collection of data, often in large amounts – Behaviors difficult to observe can be studied – Researcher can compare individual responses Weakness – Subjects may provide misleading responses (intentional deception, social desirability bias)

Table of Contents 7/24/03 35 Beware!!! Beware of “False Consensus” It’s our tendency to overestimate the extent to which others share our beliefs and behaviors. This is why we must do research.

Table of Contents 7/24/ Longitudinal Study The study of a large group of people over an extended period of time *Commonly used by developmental researchers * Possibly conducted through the use of surveys

Table of Contents 7/24/03 37 Strength and Weaknesses of the Longitudinal Method Strengths – More accurate conclusions can be drawn due to the use of the same subjects Weaknesses – Attrition of subjects – Length – Expense due to the length

Table of Contents 7/24/ Comparative/Cross-sectional study The study and comparison of subjects of various ages at the same time *Commonly used by developmental researchers * Possibly conducted through the use of surveys

Table of Contents 7/24/03 39 Strengths and Weaknesses of the Comparative/Cross-sectional study Strengths – Faster than longitudinal studies – More cost effective Weakness – Results may not be as accurate due to being based on averages

Table of Contents 7/24/ Cross-cultural Study Technique using the basic principle of the cross-sectional study, however, the subjects are of various cultures rather than age groups – Strengths and weaknesses are similar to those found with the cross section study

Table of Contents 41 Did you know… your chances of being dealt either of the hands below is precisely the same: 1 in 2,598,960? Myers 8 th ed. Hand One ? Hand Two ?

Table of Contents 7/24/03 42 IV. Statistics and Research: Drawing Conclusions Statistics – using mathematics to organize, summarize, and interpret numerical data

Table of Contents 7/24/03 43 A. Descriptive Statistics Descriptive statistics: organizing and summarizing data typically done with graphs/charts Graphs to know: – Frequency distribution – Frequency polygon (line graph) – Histogram/ Bar graph * Note: Make sure you read Appendix B

Table of Contents 7/24/ Descriptive Statistics: Measures of Central Tendency Measures of central tendency = typical or average score in a distribution – Mean: arithmetic average of scores – Median: score falling in the exact center once the numbers are put in order – Mode: most frequently occurring score * Note: the mean is sensitive to extremes. If the distribution is skewed, use the median.

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Table of Contents 7/24/ Descriptive Statistics: Normal Distribution A symmetrical “bell shaped” curve which represents the pattern in which many human characteristics fall within a given population

Table of Contents 7/24/ Descriptive Statistics: Skewed Distributions Positively Skewed Distribution – A distribution in which the extreme falls to the right of the norm, and the majority of scores fall into the lower response categories Negatively Skewed Distribution – A distribution in which the extreme falls to the left of the norm, and the majority of scores fall into the higher response categories

Table of Contents 7/24/03 48 Is it positively or negatively skewed? Mode Median Mean One Family Income per family in thousands of dollars Example of a Skewed Distribution

Table of Contents 7/24/ Descriptive Statistics: Variability Variability = the extent that scores differ in a given distribution Three Measures of Variability 1. Standard deviation = a measure of how much scores vary around the mean high standard deviation = high variability in data set low standard deviation = low variability in data set 2. Variance = standard deviation squared (V= SD 2 ) Disadvantage = data isn’t presented in its original collected form 3. Range = the highest score minus the lowest +1

Table of Contents 7/24/ Descriptive Statistics: Correlation (No need to write the same thing twice, just put “See correlation notes”.)

Table of Contents 7/24/03 51 B.Inferential Statistics Inferential statistics: interpreting data, drawing conclusions and generalizing to the larger population

Table of Contents 7/24/03 52 Random Question… Do you know what Mark Twain said about statistics?

Table of Contents 7/24/03 53 Inferential Statistics cont. When using inferential statistics, the answer should be YES to the following questions. Hypothesis testing: do observed findings support the hypothesis? Statistical significance = is the probability that the observed findings are due to chance very low – Very low = less than 5 chances in 100,.05 level (5%) – Are findings real or due to chance? Application – can the findings be generalized to the larger population?

Table of Contents 7/24/03 54 THE END! Study “Beyond Recognition” Note cards are due TEST – 25 minute free response – 100 multiple choice