Splash Screen

Chapter Objectives · Section 1What Is Research?

Describe the process in which psychologists approach a research issue and conduct the research to test a hypothesis, solve a problem, or confirm previous research.

Chapter Objectives · Section 2Problems and Solutions in Research

Discuss how psychologists must recognize and resolve errors as they conduct research.

Chapter Objectives · Section 3Statistical Evaluation

Recognize that psychologists must collect and evaluate evidence to support their hypotheses.

Main Idea

Psychologists must first decide how to approach the research issue. Then psychologists conduct the research in one of a variety of ways to test a hypothesis, solve a problem, or confirm previous findings.

Vocabulary

• sample

• naturalistic observation

• case study

• survey

• longitudinal study

• cross-sectional study

• correlation

• hypothesis

• variable

• experimental group

• control group

Objectives

• Describe the process of psychological research and the scientific method.

• Name the different types of psychological research.

Pre-Research Decisions

• Researchers begin by asking a specific question about a limited topic or hypothesis.

• Then they collect evidence.

• A sample is a relatively small group of the total population under study.

• A sample must be representative.

Pre-Research Decisions (cont.)

• Ways to avoid a nonrepresentative sample:

– Take a purely random sample.

– Deliberately pick individuals who represent the various subgroups in the population being studied, also known as a stratified sample.

Jane Goodall

Methods of Research

• The goals of research are to:

– Describe behavior

– Explain its causes

– Predict the circumstances under which certain behaviors may occur again

– To control certain behaviors

Methods of Research (cont.)

• Methods of research used to accomplish these goals:

– Naturalistic observations

– Case studies

– Surveys

– Longitudinal Studies

– Cross-Sectional Studies

– Correlations

– Experiments A Correlation Study

Methods of Research (cont.)

• Every experiment has:

– hypothesis

– variables (independent and dependent)

– experimental group

– control group

Experimental Research

Methods of Research (cont.)

• Ethics are the methods of conduct, or standards, for proper and responsible behavior.

• The APA has a list of ethical principles that psychologists must follow.

Main Idea

The investigation of psychological issues is a painstaking process. Psychologists must recognize and resolve errors while doing research.

Vocabulary

• self-fulfilling prophecy

• single-blind experiment

• double-blind experiment

• placebo effect

Objectives

• Summarize the methodological hazards of doing research.

• Examine experimental procedures psychologists use to avoid bias.

Problems and Solutions in Research

• A self-fulfilling prophecy is a situation in which a researcher’s expectations influence that person’s own behavior, and thereby influence the participant’s behavior.

Avoiding a Self-Fulfilling Prophecy

• Ways to avoid self-fulfilling prophecy:

– Single-blind experiment

– Double-blind experiment

Single-Blind and Double-Blind Experiments

The Milgram Experiment

• In the 1960s, Stanley Miligram wanted to determine whether participants would administer painful shocks to others merely because an authority figure had instructed them to do so.

• The result implied that ordinary individuals could easily inflict pain on others if such orders were issued by a respected authority.

The Milgram Experiment (cont.)

• His experiment, although no one was actually shocked, was controversial.

• Today, experiments are required to submit a plan to a Human Subjects Committee.

The Placebo Effect

• The placebo effect is a change in a participant’s illness or behavior that results from a belief that the treatment will have an effect rather than from the actual treatment.

Main Idea

Psychologists must collect and evaluate evidence to support their hypotheses.

Vocabulary

• statistics

• descriptive statistics

• frequency distribution

• normal curve

• central tendency

• variability

• standard deviation

• correlation coefficient

• inferential statistics

Objectives

• Recognize types of descriptive statistics.

• Describe inferential statistics.

Statistical Evaluation

• Statistics consist of the branch of mathematics concerned with summarizing and making meaningful inferences from collections of data.

Kate’s Data

Descriptive Statistics

• Descriptive statistics involve the listing and summarizing of data in a practical, efficient way.

• One of the first steps that researchers take to organize their data is to create frequency tables and graphs.

Descriptive Statistics (cont.)

• A frequency distribution is a way of arranging data so that we know how often a particular score or observation occurs.

A Frequency Distribution

Descriptive Statistics (cont.)

• Types of graphs:

– Histogram

– Frequency polygon/frequency curve

A Frequency Polygon

Descriptive Statistics (cont.)

• A normal curve is a graph of frequency distribution shaped like a symmetrical, bell-shaped curve.

A Normal Curve

Descriptive Statistics (cont.)

• A common way of summarizing is to measure the central tendency.

• Distributions also differ in their variability.

Measure of Central Tendency

Descriptive Statistics (cont.)

• Two commonly used measures of variability are:

– Range

– Standard deviation

Standard Deviation

Descriptive Statistics (cont.)

• Standard deviation is a better measure because it uses all of the data points.

• A correlation coefficient describes the direction and strength of the relationship between two sets of observations.

• The most commonly used measure is the Pearson correlation coefficient (r).

Descriptive Statistics (cont.)

• A coefficient with a plus sign (+) indicates a positive correlation.

• A coefficient with a minus sign (–) indicates a negative coefficient.

• A scatterplot is a graph of scores that demonstrates the direction of the relationship between two variables.

A Scatterplot

Inferential Statistics

• Psychologists also want to make generalizations about the population from which the participants come, so they use inferential statistics.

• Inferential statistics are numerical methods used to determine whether research data support a hypothesis or whether results were due to change.

Inferential Statistics (cont.)

• Researchers must perform a variety of statistical tests, called measures of statistical significance, to determine that their results are not due to chance.

• For many traits in a large population, the frequency distribution follows the normal curve.

Inferential Statistics (cont.)

• Many researchers say that if the probability that their results were due to chance is less than 5%, they do not think the results were due to chance.

• The results would then be considered statistically significant.