2 The Scientific Approach EmpiricismBasic assumption: events are governed by some lawful orderGoals:Measurement and descriptionUnderstanding and predictionApplication and controlGoal of theory testing in science: refutation not provingPsychologists assume that behavior is governed by discernible laws or principles; these just need to be uncovered.The goals of the scientific enterprise of psychology are:To measure and describe a phenomenon, for example sociability.To understand and predict…psychologists form hypotheses about how variables interact. A hypothesis is a tentative statement about the relationship between 2 or more variables. Variables are the things that are observed or controlled in a study.To apply and control…information gathered by scientists may be of some practical value in helping to solve problems in schools, businesses, mental health centers, etc.
3 Steps of the Scientific Method 1. Developing a Hypothesis:-Hypothesis: A statement predicting the outcome of a scientific study or describing the relationship among variables in a study.
4 Steps of the Scientific Method 2. Design test: A hypothesis must undergo rigorous tests before it will be accepted as a legitimate theory.To make a test controlled, one must account for the independent variable.Independent Variable: A stimulus condition that the experimenter changes independently of all other carefully controlled conditions in the experiment.
5 Steps of the Scientific Method 3. Collect data: getting information by direct observation that relies only on the independent variable and not on the experimenter’s hopes. This data is called the dependent variable.Dependent Variable: The measured outcome of a study, or the response of the subjects in the study.
6 Steps of the Scientific Method 4. Analyzing the results: This step consists of looking at the data collected and seeing if it supports or disproves the hypothesis.
7 Steps of the Scientific Method 5. Publishing, criticizing and replicating the results: The last step of the scientific method is to have the results withstand the criticism and scrutiny of the science community.Replicate: To do a study over to see if the same results are obtained. To control for bias, the replication is most often done by someone other than the original researcher.
8 The Scientific Method: Terminology Operational definitions are used to clarify precisely what is meant by each variableParticipants or subjects are the organisms whose behavior is systematically observed in a studyData collection techniques allow for empirical observation and measurementPsychologists use operational definitions to clarify what their variables mean…what exactly is sociability?Researchers use procedures for making empirical observations and measurements, including direct observation, questionnaires, interviews, psychological tests, physiological recordings, and examination of archival records.They depend on statistics to analyze data and decide whether hypotheses were supported…observations are converted into numbers, which are then compared.They share their findings through reports at scientific meetings and in scientific journals…this way others can evaluate new research findings and build new ideas.Using the scientific approach, scientists state EXACTLY what they are talking about, resulting in clarity of communication. The scientific method also yields more accurate and dependable information than, for example, speculation.Research methods consist of differing approaches to the observation, measurement, manipulation, and control of variables in empirical studies.
9 The Scientific Method: Terminology Statistics are used to analyze data and decide whether hypotheses were supportedFindings are shared through reports at scientific meetings and in scientific journals – periodicals that publish technical and scholarly materialAdvantages of the scientific method: clarity of communication and relative intolerance of errorResearch methods: general strategies for conducting scientific studiesPsychologists use operational definitions to clarify what their variables mean…what exactly is sociability?Researchers use procedures for making empirical observations and measurements, including direct observation, questionnaires, interviews, psychological tests, physiological recordings, and examination of archival records.They depend on statistics to analyze data and decide whether hypotheses were supported…observations are converted into numbers, which are then compared.They share their findings through reports at scientific meetings and in scientific journals…this way others can evaluate new research findings and build new ideas.Using the scientific approach, scientists state EXACTLY what they are talking about, resulting in clarity of communication. The scientific method also yields more accurate and dependable information than, for example, speculation.Research methods consist of differing approaches to the observation, measurement, manipulation, and control of variables in empirical studies.
10 Experimental Research: Looking for Causes Experiment = manipulation of one variable under controlled conditions so that resulting changes in another variable can be observedDetection of cause-and-effect relationshipsIndependent variable (IV) = variable manipulatedDependent variable (DV) = variable affected by manipulationHow does X affect Y?X= Independent Variable, and Y= Dependent VariableAn experiment is a research method where there is manipulation of one variable under carefully controlled conditions so that resulting changes in another variable can be observed…key word “resulting.”Experiments are very powerful in that they allow for detection of cause-and effect relationships…Does X cause Y?The IV is the variable that the experimenter controls or manipulates…the DV is the variable thought to DEPEND (at least in part) on manipulation of the IV.If we wanted to know how X affects Y, X would be the IV, and Y would be the DV.
11 Experimental and Control Groups Experimental group – subjects who receive some special treatment in regard to the independent variableControl group – similar subjects who do not receive the special treatmentLogic:Two groups alike in all respects (random assignment)Manipulate independent variable for one group onlyResulting differences in the two groups must be due to the independent variableExtraneous and confounding variablesIn an experiment, the investigator assembles two groups who are as alike as possible, an experimental group (who receives a special treatment in regard to the independent variable) and a control group (who do not receive the special treatment). Then, after they administer the treatment, if the two groups differ on the dependent variable, it MUST be due to the treatment.An extraneous variable is a variable, other than the independent variable, that may influence the dependent variable.Confounding of variables occurs when participants in one group of subjects are inadvertently different in some way from participants in the other group, influencing outcome.Random assignment of subjects is used to control for confounding variables.
12 Experimental Designs: Variations Expose a single group to two different conditionsReduces extraneous variablesManipulate more than one independent variableAllows for study of interactions between variablesUse more than one dependent variableObtains a more complete picture of effect of the independent variableExperimental designs can be quite complex. These are a few of the ways designs can vary.Sometimes, a single group can be used for both experimental and control conditions…for example, you might study the effects of having the radio on when people work on an assembly line…you’d collect data from the same group of workers twice, once with the radio on and once with it off.Researchers can also manipulate more than one IV to see what the combined effect is…sometimes, the effect of one variable depends on the effect of another…for example, you might find that having the radio on increases productivity in workers, but only in the morning…in this example, time of day interacts with the effects of the radio.Researchers can also use more than one dependent variable in a single study to get a more complete picture of the effect of the independent variable. For example, we might measure not only number of pieces workers finish when the radio is allowed to be on while they work, but also worker satisfaction, absenteeism, and attitude. Having 1 day less a month absenteeism might make up for a slight decrease in productivity.
13 Descriptive Research Methods Strategies for observing and describing behaviorTypically words instead of numbers (qualitative)Do not manipulate anything in the research
14 Observations Observe behavior by watching and recording information Naturalistic – in the natural setting, creates a purer resultLab – more controlled, but less natural
15 Case Studies One individual studied in great detail Typically rare casesYou collect information in several ways
16 Surveys Asking questions about a specific topic Very direct Use interviews, questionnaires, surveys
17 Statistics and Research Statistics – using mathematics to organize, summarize, and interpret numerical dataDescriptive statistics: organizing and summarizing dataInferential statistics: interpreting data and drawing conclusions – use of probabilityStatistics - using mathematics to organize, summarize, and interpret numerical data…statistical analyses allow researchers to draw conclusions about their data.Statistics are a part of everyday modern life…batting averages, economic projections, popularity ratings for TV shows, etc.There are two basic types of statistics, descriptive and inferential.Descriptive statistics are used to organize and summarize data to provide some sort of overview.Inferential statistics use the laws of probability to allow researchers to interpret data and draw conclusions.
18 Descriptive Statistics: Measures of Central Tendency Measures of central tendency = typical or average score in a distributionMean: arithmetic average of scoresMedian: score falling in the exact centerMode: most frequently occurring scoreWhich most accurately depicts the typical?Measures of central tendency are used to describe the typical or average score in a distribution.The mean is the arithmetic average and is therefore sensitive to extreme scores.The median is the score that falls exactly in the center of the distribution.The mode is the most frequently occurring score.Which one is the most accurate depiction of the typical score? It depends on the data, as depicted on the next slide.
19 Descriptive Statistics: Variability Variability = how much scores vary from each other and from the meanStandard deviation = numerical depiction of variabilityHigh variability in data set = high standard deviationLow variability in data set = low standard deviationVariability refers to how much scores in a set of data vary from one another and from the mean…the standard deviation is a numerical index of variability.If the variability in a data set is high, the standard deviation will be a higher number than if the variability is low, as is evident in Figure 2.13.
20 Normal Distribution A normal distribution is a bell shaped curve. A standard deviation of 1 accounts for about 68% of responses.
21 Descriptive Statistics: Correlation When two variables are related to each other, they are correlated.Correlation = numerical index of degree of relationshipCorrelation expressed as a number between 0 and 1Can be positive or negativeNumbers closer to 1 (+ or -) indicate stronger relationshipA correlation exists when two variables are related to each other.The correlation coefficient is a numerical index of the strength and direction of association between two variables.A correlation is expressed as a number between 1 and 0, and the number may be positive or negative.The closer to 1 the number is, whether +1 or –1, the stronger the relationship between the variables…for example, a correlation of .17 is pretty weak, while a correlation of -.89 is pretty strong.The positive/negative dimension of the correlation coefficient expresses the direction of the relationship. If two variables are positively correlated, they co-vary in the same direction…as scores on one variable go up, scores on the other variable go up too…if two variables are negatively correlated, the variables co-vary in the opposite direction…as one goes up, the other goes down.
24 Which of the following correlation coefficients presents the strongest relationship between the variables?a. .02b. -.67c. .55d. -.14
25 Correlation: Prediction, Not Causation Higher correlation coefficients = increased ability to predict one variable based on the otherSAT/ACT scores moderately correlated with first year college GPA2 variables may be highly correlated, but not causally relatedFoot size and vocabulary positively correlatedDo larger feet cause larger vocabularies?The third variable problemAs a correlation increases in strength (closer to – or + 1), the ability to predict one variable based on knowledge of the other variable increases.SAT/ACT scores are correlated with first year college GPA at a moderate .40 to this may not be perfect, but it allows admissions committees to predict with some accuracy how well a prospective student will do in college.Although correlation may allow prediction, it does not infer cause-and-effect.For example, a strong positive correlation has been shown between foot size in children and vocabulary…as foot size increases, so does vocabulary. Do bigger feet make children learn more words? No. It is a third variable, age, which causes both feet and vocabulary to grow.
26 Inferential Statistics: Interpreting Data and Drawing Conclusions Hypothesis testing: do observed findings support the hypotheses?Are findings real or due to chance?Statistical significance = when the probability that the observed findings are due to chance is very lowVery low = less than 5 chances in 100/ .05 levelOther factors might account for the resultsResearchers use inferential statistics to determine whether their data support their hypotheses…with these statistical methods, they can interpret data and draw conclusions.Inferential statistics use the laws of probability to allow researchers to determine how likely it is that their findings are real, that is, not due to chance.Statistical significance is said to exist when the probability that the observed findings are due to chance is very low…many psychologists see “very low” as fewer than 5 chances in 100 that results are not real…the .05 level of significance.
27 SamplingRepresentative Sample: A sample obtained in such a way that it reflects the distribution of important variables in the larger population in which the researcher are interested-variables such as age, SES, ethnicity, education….
28 Evaluating Research: Methodological Pitfalls Sampling biasPlacebo effects – is not always uniform – cost factors and perceived painDistortions in self-report data:Social desirability biasResponse setExperimenter biasthe double-blind solutionResearch protocol of clinical trial for drugs – FDA in U.S.Sampling bias – when a sample is not representative of the population…poll only men, may get a different outcome if the population is both male and female.Placebo effects – when a participant’s expectations lead them to experience some change even though they receive empty, fake, or ineffectual treatment…cured by a sugar pill.Distortions in self-report data:Social desirability bias – a tendency to give socially approved answers to questions about oneself…did you vote?Response set – a tendency to respond to questions in a particular way (agree with everything, etc.).Experimenter bias – when a researcher’s expectations or preferences about the outcome of a study influence the results obtained…researchers see what they want to see – errors are usually in favor of the hypothesis…similarly, researchers may unintentionally influence the behavior of their subjects, possibly through body language, smiles, etc. To control for this problem, a double-blind procedure in which neither subjects nor experimenters know which subjects are in the experimental and which are in the control groups is used…a non-directly involved researcher keeps track of everything.
29 Internet Psychological Research Internet-mediated research refers to studies in which data collection occurs over the web.Possible AdvantagesSamples that are much larger and much more diverse than the samples used in lab researchHave the potential to yield more diverse and representative samples
30 Internet Psychological Research Potential DisadvantagesSampling bias resulting from self-selection may be a more troublesome issue in Internet-mediated researchWeb users tend to be younger, brighter, and more affluent than nonusersData are collected under far less controlled conditions than in traditional studies
31 Ethics in Psychological Research: Do the Ends Justify the Means? The question of deceptionThe question of animal researchControversy among psychologists and the publicEthical standards for research: the American Psychological AssociationEnsures both human and animal subjects are treated with dignityThe question of deception:Is it OK to make subjects think they are hurting others? Have homosexual tendencies? Think they are overhearing negative comments about themselves?The question of animal research:Controversy regarding humane treatment of animals vs. no use of animals in research.These and other ethical issues have led the American Psychological Association (APA) to develop a set of ethical standards for research, to ensure that both human and animal subjects are treated with dignity.
32 Ethics in Psychological Research: Do the Ends Justify the Means? Tuskegee Syphilis Study: