Unit 2: Research & Statistics n Psychology deals with many experiments and studies n WHO? Every experimenter must decide on a SAMPLE, which is a group of people (subjects) to do the experiment on –Make sure that it is a RANDOM SAMPLE, which means that every person an equal chance of being represented from the POPULATION (drawing names from a hat »EX: a psychologist might choose every 20th name from a school list

n Ways to ensure that a sample is random: (1) single blind experiment: the participants do not know if they have received a “real” drug or a “sugar pill” *this is to be sure that the results are more accurate (mind over matter) (2) double blind experiment: neither the participants nor the experimenter knows who received what so the researcher remains unbiased

n WHAT? Parts of a Research Study A) Hypothesis: educated guess about the outcome of the study B) Variables: conditions and behaviors that you are testing in the study 1. Independent variable: experimenters change so they can observe the effects; what they are testing 2. Dependent variable: the part that changes with relation to the independent variable EX: the # of hours you study (independent variable) affects your performance on an exam (dependent variable)

n C) Groups: (1) Experimental Group: those people who are exposed to the independent variable (“real drug”) (2) Control Group: not exposed to the independent variable *you must have a control group in every study so that you can compare your results *called the “placebo” group (“sugar pill”) (3) Replication: every study must be replicated (repeated) to make sure the results are accurate

n HOW? The goal of research is to describe behavior, explain its causes, and to predict how it occurs n Ways to Conduct Research : (1) Naturalistic Observation: go to a natural environment and study behavior EX: when a researcher goes to an African Jungle to study lions in the wild (2)Case Study: an intensive study of a person or group; not random

3) Survey: interviews, questionnaires (-) always a truth issue; is the person taking the survey being completely honest? (+) takes less time (+) eliminates the possibility that the researcher will influence answers

4. Longitudinal Studies: study of the same group of people at regular intervals over a period of years to determine whether the behavior is changed (-) time consuming (-) some participants might die, or move EX: a researcher decides to study your sleeping patterns; you have to be interviewed every 2 years and fill out a questionnaire until your 75 years old

(5) Cross-sectional Studies: researchers organize people in groups according to age and every group is surveyed and questioned (+) less expensive than longitudinal EX: a researcher conducts an experiment in which they showed 3, 4, and 5 year olds a violent movie and then gave them a questionnaire

n AND THE RESULTS ARE IN…. Once the data is collected, what can you do with it? >Correlations: describe how 2 sets of data relate to each other; no cause and effect just a relationship (1) Positive Correlation: one increases, the other increases EX: there is a positive correlation between students’ grades and attendance in school (1 goes up, the other goes up)

(2) Negative Correlation: one increases, the other decreases EX: there is a negative correlation between the number of hours you spend practicing your shooting technique and the number of missed free throws (as hours increase, the number of missed free throws decrease)

Negative Correlation

Zero Correlation

n Correlation Coefficients: describes a relationship between 2 sets of observations *Most commonly used is the Pearson Correlation Coefficient (r) *Correlations range from +1 to –1 including 0; an r near +1 or –1 means there is a strong relationship, while an r of 0 means there is a weak relationship

>Normal Curve: (or bell shaped curve) when you graph the data, it appears as a curve that is equal on both sides

GRAPHS 1. Label what each axis means (EX: height, weight) weight height

2. Choose an interval for each axis once you look at the data table *don’t start with “0” *must be even intervals Weight

3. Do not connect the dots for correlation graphs 4. Always have a title (use names of both axis) EX: Height vs. Weight

STATISTICS *Branch of math that allows researchers to organize and evaluate data they collect *Measures of Central Tendency: 1. Mean 2. Median 3. Mode 4. Range 5. Frequency distribution

MEAN n Add up #’s and divide by how many numbers you have EX: Added: 30 30/5 = 6 Mean = 6

MEDIAN n Place #’s in order and choose the midpoint *include zeros *include repeating #’s *if even #, find average EX: * 4 87

MODE n Occurs most often EX: Mode = 2 *if there are 2 modes, it is bimodal

RANGE n Largest # - Smallest # EX: Range : 30-2=28

Frequency Distribution n (FD) n Put #’s in order and list how often they occur EX: FD