Research and Research and StatisticsStatistics

AP PsychologyAP Psychology

Questions:Questions:

►Why do scientists conduct research?Why do scientists conduct research? answeranswer

Questions that Social Questions that Social Psychologists wanted to Psychologists wanted to

explore:explore:►What impact does attractiveness have What impact does attractiveness have

on perception?on perception?►How do we explain peoples’ behavior?How do we explain peoples’ behavior?

Famous ExperimentFamous Experiment

►What are the reasons for attitudes or What are the reasons for attitudes or prejudices?prejudices?

►Why do we conform?Why do we conform?►Why are some people altruistic?Why are some people altruistic?

►Describe a phenomenonDescribe a phenomenon

►Make predictions aboutMake predictions aboutthe phenomenonthe phenomenon

►Control variablesControl variables

►Explain phenomenon Explain phenomenon with some degree of confidencewith some degree of confidence

4 Main Goals of Psychological 4 Main Goals of Psychological Research:Research:

In order to conduct good In order to conduct good psychological research one psychological research one

must:must: Use the scientific method.Use the scientific method.

►Have a clear operational definition.Have a clear operational definition. Allows for replication.Allows for replication.

►Have informed consent.Have informed consent.►Follow Follow APA guidelinesAPA guidelines..

Various Types of Research MethodsVarious Types of Research MethodsVideoVideo

►Descriptive Research: Scientists use Descriptive Research: Scientists use naturalistic observations, case naturalistic observations, case studies, and surveys tstudies, and surveys to o describe describe and predict behavior and mental and predict behavior and mental processesprocesses. .

Various Types of Various Types of Research MethodsResearch Methods

►Correlational Research: predicts Correlational Research: predicts naturally occurring relationships.naturally occurring relationships.

Various Types of Various Types of Research MethodsResearch Methods

►Experimental Research: Scientists use Experimental Research: Scientists use experimentsexperiments to control variables and to control variables and to establish to establish Cause and EffectCause and Effect RelationshipsRelationships (in which one variable (in which one variable can be shown to have caused a can be shown to have caused a change in another.)change in another.)

DescriptiveDescriptiveResearchResearch

► Naturalistic Observation:Naturalistic Observation: Seeing subjects in natural Seeing subjects in natural

environmentenvironment Best way to gather Best way to gather

descriptive data.descriptive data. Problem- when people Problem- when people

know that they are being know that they are being watched, they act watched, they act differently. (Hawthorn differently. (Hawthorn effect) effect)

Test 1Test 1 Video 1Video 1 Video 2Video 2

► Case Studies: Case Studies: Intense examination of a Intense examination of a

phenomenon. phenomenon. Useful when something Useful when something

is new and complex.is new and complex. Problem- limited to what Problem- limited to what

researchers consider researchers consider important.important.

Surveys Surveys ►Researchers use questionnaires and Researchers use questionnaires and

interviews to gather information about interviews to gather information about behavior, beliefs, and opinions.behavior, beliefs, and opinions.

►Gives a broad view of a large group.Gives a broad view of a large group.►Validity depends on Validity depends on representativenessrepresentativeness

and and how questions are wordedhow questions are worded. . ►Problem- people are reluctant to say Problem- people are reluctant to say

what they really believe, say what is what they really believe, say what is desired.desired.

Descriptive Research

Correlation:Correlation:

► Used to say that two traits or Used to say that two traits or behaviors accompany one another and behaviors accompany one another and the the Correlation CoefficientCorrelation Coefficient measures measures the relationship between the two.the relationship between the two.

►Correlation does not mean Causation!!!Correlation does not mean Causation!!!►Types of correlation:Types of correlation:

Positive- two variables same directionPositive- two variables same direction Negative- two variables opposite directionNegative- two variables opposite direction

Correlation CoefficientCorrelation Coefficient

► A number that A number that measures the measures the strength of a strength of a relationship.relationship.

► Range is from -1 to Range is from -1 to +1+1

► The relationship The relationship gets weaker the gets weaker the closer you get to closer you get to zero.zero.

Which is a stronger Which is a stronger correlation?correlation?

► -.13 or +.38-.13 or +.38► -.72 or +.59-.72 or +.59► -.91 or +.04-.91 or +.04

Experiments:Experiments:

► Establish a Cause and Effect relationship.Establish a Cause and Effect relationship.► Allow researchers to control variables. Allow researchers to control variables.

By manipulating variables, researchers view By manipulating variables, researchers view effects.effects.

Types of Variables: Types of Variables: ►Independent- manipulated factor. Independent- manipulated factor. ►Dependent- factor that is observed and Dependent- factor that is observed and

measured. (depends on the application of the measured. (depends on the application of the independent variable)independent variable)

► Confounding a.k.a.Random Variables-Confounding a.k.a.Random Variables-uncontrolled factors in research design. uncontrolled factors in research design.

Experimental Method:Experimental Method:

► 1.1. Observe some aspect of the universe. Observe some aspect of the universe. ► 2.2. Invent a tentative description, called a Invent a tentative description, called a

hypothesishypothesis, that is consistent with what you , that is consistent with what you have observed. have observed.

► 3.3. Use the hypothesis to make predictions. Use the hypothesis to make predictions. ► 4.4. Test those predictions by experiments or Test those predictions by experiments or

further observations and modify the further observations and modify the hypothesis in the light of your results. hypothesis in the light of your results.

► 5.5. Repeat steps 3 and 4 until there are no Repeat steps 3 and 4 until there are no discrepancies between theory and discrepancies between theory and experiment and/or observation. experiment and/or observation.

How do I pick the people to How do I pick the people to study?study?

► Pick a Pick a samplesample of people from a of people from a populationpopulation so that you can so that you can generalizegeneralize your findings. your findings. Regardless of research design)Regardless of research design) Population Population Random Sample Random Sample Random Random

Assignment Assignment Control Group OR Experimental Control Group OR Experimental Group Group

Larger samples yield more reliable results Larger samples yield more reliable results (External Validity) (External Validity)

So now, what do we do with all So now, what do we do with all the data collected???????the data collected???????

►We use STATISTICS! Yay…..We use STATISTICS! Yay…..

Important stuff to know about Important stuff to know about data…data…

► In order for data to be considered In order for data to be considered worthy or good, sound data it must worthy or good, sound data it must be…be… Reliable- stable and consistentReliable- stable and consistent Valid- it is reporting what it set out to Valid- it is reporting what it set out to

reportreport

Statistical Analysis of Research Results: Statistical Analysis of Research Results: Descriptive or Inferential?Descriptive or Inferential?

►Statistics are methods for Statistics are methods for demystifying and making meaning demystifying and making meaning from data.from data.

►Numbers have little meaning unless it is Numbers have little meaning unless it is organized. An organized list allows us organized. An organized list allows us to see clusters or patterns in data. to see clusters or patterns in data.

►Graphing allows us to see some level of Graphing allows us to see some level of meaning from numbers. (Pie Charts, meaning from numbers. (Pie Charts, Line Graphs, Frequency PolygonLine Graphs, Frequency Polygon

Descriptive Statistics:Descriptive Statistics:

► Used to Used to describedescribe and and presentpresent data. data.► They can tell us the difference between They can tell us the difference between

two or more groups. two or more groups. ► Basic categories of DS areBasic categories of DS are

1. Central Tendency1. Central Tendency 2. Variability2. Variability 3. Correlation3. Correlation

Central TendenciesCentral Tendencies

►A way to describe the typical or A way to describe the typical or average score distribution.average score distribution.

►Mean-Mean- average, can be skewed. average, can be skewed.►Median-Median- best indicator of central best indicator of central

tendency, middle score.tendency, middle score.►Mode-Mode- Most frequently occurring score. Most frequently occurring score.

Variability:Variability:

► Indicates how much spread there is in Indicates how much spread there is in a distribution.a distribution.

►Range- Range- difference between lowest and difference between lowest and highest score.highest score.

►Variance- Variance- how different scores are how different scores are from each otherfrom each other..

►Standard Deviation- Standard Deviation- most common most common measure of variability. (how far each measure of variability. (how far each value is from the mean.) value is from the mean.)

Let’s practice with Central Let’s practice with Central TendenciesTendencies

►What options does Mars Co have when What options does Mars Co have when filling bags of M&Ms in regard to color?filling bags of M&Ms in regard to color?

►FIXED…..RANDOM…..You decide!FIXED…..RANDOM…..You decide!

Choose a sample from the Choose a sample from the population…..population…..

Propose a hypothesis by recording a % on Propose a hypothesis by recording a % on worksheet. (worksheet. (f f = frequency) Calculate %.= frequency) Calculate %.

Observe and record actual colors in your Observe and record actual colors in your sample. (how closely do they match?)sample. (how closely do they match?)

►Will you alter your hypothesis?Will you alter your hypothesis?

Get into groups of 5 people. Record data.Get into groups of 5 people. Record data.►Will you alter your hypothesis?Will you alter your hypothesis?

Get into 2 big groups. Record data. Get into 2 big groups. Record data. ►Will you alter your hypothesis?Will you alter your hypothesis?

Get into 1 group. Record data.Get into 1 group. Record data.►Will you alter your hypothesis?Will you alter your hypothesis?

So what…So what…

►…….does this tell us about sampling?.does this tell us about sampling?►……does this tell us about randomness?does this tell us about randomness?►……does this tell us about the does this tell us about the

relationship between research and relationship between research and statistics?statistics?

Normal/Bell Shaped Curve:Normal/Bell Shaped Curve:Intelligence and IQ Intelligence and IQ

Correlation:Correlation:

►Used to describe the relationship Used to describe the relationship between two variables. (co- relation)between two variables. (co- relation)

►Measured in numbers from -1.0 to +1.0.Measured in numbers from -1.0 to +1.0.► -1.0 indicates negative relationship-1.0 indicates negative relationship►0 indicates no relationship0 indicates no relationship►+1.0 indicates positive relationship+1.0 indicates positive relationship►Scatter plots are used for visual Scatter plots are used for visual

representation.representation.

Inferential Statistics:Inferential Statistics:

► Provides the researcher with a measure of Provides the researcher with a measure of confidence that the difference between confidence that the difference between groups is large enough to be important groups is large enough to be important (or small enough to be (or small enough to be insignificant.) In other words, IS provide insignificant.) In other words, IS provide a measure of a measure of how likelyhow likelyit was that results came about by it was that results came about by chancechance. . In summary it answers the question- was In summary it answers the question- was the difference mostly due to the the difference mostly due to the Independent Variable Independent Variable rather than rather than chance chance factors.factors.

Statistically Significant?Statistically Significant? (Tests of Statistical (Tests of Statistical

Significance.)Significance.)► t-test: establishes if results were t-test: establishes if results were

by chance or because of IV.by chance or because of IV.

►ANOVA: compares means of 2 or ANOVA: compares means of 2 or more groupsmore groups