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Wednesday, March 10, 2010

Research Methods in Psychology- part 3

Ethical Considerations

In the past, researchers performed all kinds of questionable experiments in the name of science. For example, in one famous experiment, psychologist Stanley Milgram led his subjects to believe that they were giving painful electric shocks to other people. Many people consider this experiment unethical because it caused the subjects emotional discomfort. Today, researchers must abide by basic ethical norms when conducting research. Most important, they must consider whether they might harm their human or animal subjects while doing research.

Research with Human Subjects

Researchers must get informed consent from their subjects before beginning research. Informed consent means that subjects must know enough about the research to decide whether to participate, and they must agree to participate voluntarily. Furthermore, researchers have an ethical obligation to prevent physical and mental harm to their subjects. If there is any risk of harm, they must warn subjects in advance. Researchers also must allow subjects to withdraw from a study at any time if they wish to stop participating. Finally, researchers have an obligation to protect the anonymity of their subjects.
Some psychological research cannot be done when subjects are fully informed about the purpose of the research, because people sometimes behave differently when under observation. To study people’s normal behavior, researchers sometimes have to deceive subjects. Deception is considered ethical only if:
  • The study will give researchers some valuable insight
  • It would be impossible to do the study without deception
  • Subjects can learn the truth about the study’s purpose and methods afterward

Research with Animal Subjects

Although most psychological research involves human subjects, some psychologists study animal subjects instead of or in addition to humans. Research with animal subjects has helped psychologists do the following:
  • Learn facts about animal species
  • Find ways to solve human problems
  • Study issues that can’t be studied using human subjects for practical or ethical reasons
  • Refine theories about human behavior
  • Improve human welfare
Many people question the ethics of animal research because it can involve procedures such as deprivation, pain, surgery, and euthanasia. Psychologists have ethical obligations to treat animal subjects humanely and to do research on animals only when the benefits of the research are clear.
People who are against animal research maintain three arguments:
  • Animals should have the same rights as humans.
  • Society should enact safeguards to protect the safety and welfare of animals.
  • Researchers should not put the well-being of humans above the well-being of animals.

Interpreting Data

After psychologists develop a theory, form a hypothesis, make observations, and collect data, they end up with a lot of information, usually in the form of numerical data. The term statistics refers to the analysis and interpretation of this numerical data. Psychologists use statistics to organize, summarize, and interpret the information they collect.

Descriptive Statistics

To organize and summarize their data, researchers need numbers to describe what happened. These numbers are called descriptive statistics. Researchers may use histograms or bar graphs to show the way data are distributed. Presenting data this way makes it easy to compare results, see trends in data, and evaluate results quickly.
Example: Suppose a researcher wants to find out how many hours students study for three different courses. Each course has 100 students. The researcher does a survey of ten students in each of the courses. On the survey, he asks the students to write down the number of hours per week they spend studying for that course. The data look like this:
Hours of Study per Week
Course A Course B Course C
Student Hours per week Student Hours per week Student Hours per week
Joe 9 Hannah 5 Meena 6
Peter 7 Ben 6 Sonia 6
Zoey 8 Iggy 6 Kim 7
Ana 8 Louis 6 Mike 5
Jose 7 Keesha 7 Jamie 6
Lee 9 Lisa 6 Ilana 6
Joshua 8 Mark 5 Lars 5
Ravi 9 Ahmed 5 Nick 20
Kristen 8 Jenny 6 Liz 5
Loren 1 Erin 6 Kevin 6
To get a better sense of what these data mean, the researcher can plot them on a bar graph. Histograms or bar graphs for the three courses might look like this:
Measuring Central Tendency
Researchers summarize their data by calculating measures of central tendency, such as the mean, the median, and the mode. The most commonly used measure of central tendency is the mean, which is the arithmetic average of the scores. The mean is calculated by adding up all the scores and dividing the sum by the number of scores.
However, the mean is not a good summary method to use when the data include a few extremely high or extremely low scores. A distribution with a few very high scores is called a positively skewed distribution. A distribution with a few very low scores is called a negatively skewed distribution. The mean of a positively skewed distribution will be deceptively high, and the mean of a negatively skewed distribution will be deceptively low. When working with a skewed distribution, the median is a better measure of central tendency. The median is the middle score when all the scores are arranged in order from lowest to highest.
Another measure of central tendency is the mode. The mode is the most frequently occurring score in a distribution.
Measuring Variation
Measures of variation tell researchers how much the scores in a distribution differ. Examples of measures of variation include the range and the standard deviation. The range is the difference between the highest and the lowest scores in the distribution. Researchers calculate the range by subtracting the lowest score from the highest score. The standard deviation provides more information about the amount of variation in scores. It tells a researcher the degree to which scores vary around the mean of the data.

Inferential Statistics

After analyzing statistics, researchers make inferences about how reliable and significant their data are.
Example: The researcher’s survey of the students in three classes showed differences in how long the students studied for each course. The mean number of hours for students in Course A was about eight hours, and for students in Courses B and C, the average was about six hours. Does this mean Course A requires the most hours of study? Were the differences the researcher observed in study time real or just due to chance? In other words, can he generalize from the samples of students he surveyed to the whole population of students? He needs to determine the reliability and significance of his statistics.
If researchers want to generalize confidently from a sample, the sample must fulfill two criteria:
  • It must be large and varied enough to be representative.
  • It must not have much variation in scores.
Researchers can use inferential statistics to figure out the likelihood that an observed difference was just due to chance. If it’s unlikely that the difference was due to chance, then the observed difference could be considered statistically significant. Psychologists usually consider a result to be statistically significant if such a result occurs just by chance 5 or fewer times out of every 100 times a study is done. They call this statistical significance at the p ≤ .05 level (p less than or equal to point oh-five).
However, statistical significance alone does not make a finding important. Statistical significance simply means that a result is probably not due to chance.

Quick Review

Psychological Research

  • Researchers use the terms variable, subject, sample, and population when describing their research.
  • Psychologists do research to measure and describe behavior; to understand when, why, and how events occur; and to apply knowledge to real-world problems.

The Scientific Method

  • Psychologists use the scientific method, which is a standardized way of making observations, gathering data, forming theories, testing predictions, and interpreting results.
  • Research must be replicable, falsifiable, precise, and parsimonious.

Research Methods

  • Psychologists use descriptive or correlational methods such as case studies, surveys, naturalistic observation, and laboratory observation to describe events, experiences, or behaviors and to look for links between them.
  • Researchers use tests to collect information about personality traits, emotional states, aptitudes, interests, abilities, values, or behaviors.
  • Tests must be reliable and valid.
  • Researchers use experiments to collect information about causal relationships between variables.
  • In experiments, researchers include experimental and control groups.
  • Bias is the distortion of results by a variable.
  • Types of bias include sampling bias, subject bias, and experimenter bias.

Ethical Considerations

  • Psychologists must consider ethical norms when doing research involving humans or animals.

Interpreting Data

  • Researchers analyze and interpret the data they’ve collected by using descriptive statistics and organizing their information in histograms or bar graphs.
  • Researchers use inferential statistics to determine the likelihood that a result is due simply to chance.
  • Statistical significance means that a result is probably not due to chance.

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