AP Psychology Unit 1: Scientific Foundations Of Psychology — Research Methods
Overconfidence
the tendency to be more confident than correct—to overestimate the accuracy of our beliefs and judgments.
Hindsight Bias
the tendency to believe, after learning an outcome, that one would have foreseen it
Descriptive Research Naturalistic Observation
In a naturalistic observation, researchers unobtrusively observe the behavior of subjects as it occurs in a real social setting. For example, a researcher may observe how parents interact with their children at the local mall. Naturalistic observation provides a slice of life that can be very revealing. This method minimizes artificiality, which can be a problem in laboratory studies. However, it is important to remember that the researcher cannot control the environment or any outside factors that may influence the outcome. Naturalistic observations are descriptive and thus do not explain behavior.
Correlation Studies Definition
In correlation studies researches observe or measure a relationship between variables in which changes in one variable are reflected in changes in the other variable. It is important to note that in correlation studies researches do not directly manipulate the variables. Correlations can be used to analyze the data gathered in any type of descriptive method.
Ethical Guidelines Human Research Studies
Informed consent Informed consent is the participant's agreement to take part in a study after being told what to expect. Researchers must obtain the participant's permission, or permission from a parent or guardian before the study begins. Voluntary participation All participation must be voluntary. Participants should be told they are free to withdraw from the research at any time. Deception The American Psychological Association (APA) recognizes the need for some deception in certain research areas. Deception is only justified when there is no alternative and the findings justify the use of deception because of scientific, educational, or applied value. When deception is used, subjects must be debriefed to explain the true purpose of the study and clear up any misconceptions or concerns. Confidentiality All information about participants must remain private. Researchers may not compromise the privacy of their participants. Alternative activities Many college courses include research participation as a course requirement or opportunity for extra credit. All students must be given an option to choose an alternative activity of equal value.
Descriptive Research Case Studies
A case study is an in-depth examination of an individual, small group, or situation. Case studies enable researchers to obtain detailed knowledge about rare individuals and unusual occurrences. Case studies cannot be used to establish cause-and-effect relationships. They are susceptible to inaccurate reporting and the subject's biased views.
Correlation Studies Correlation Coefficient
A correlation coefficient is a numerical value that indicates the strength and direction of the relationship between two variables. Correlation coefficients are calculated by a formula that produces a number ranging from +1.00 to -1.00. A positive correlation Indicates that two variables move or vary in the same direction. For example, studies have found a positive relationship between smoking and the incidence of lung cancer. That is, as frequency of smoking increases so does the incidence of lung cancer. A negative correlation Indicates that two variables move or vary in opposite directions. For example, studies have found a negative correlation between level of education and anger. That is, as level of education increases expressions of anger decrease. A zero correlation Indicates that there is no relationship between two variables. For example, the meta-analysis of 3,806 salespeople found that the correlation between extraversion and sales to be 0.07. Based on this finding, researches concluded that the correlation between extraversion and sales is essentially nonexistent.
The Experimental Method Testable Hypothesis
A hypothesis is a tentative statement that describes the relationship between two or more variables. A hypothesis must be testable, verifiable, and refutable. The independent variable is the factor that is manipulated or controlled by the experimenter. The dependent variable is the factor that is measured by the experimenter. It is an aspect of the participant's response that is dependent on the independent variable. Examples An experimenter wants to determine if playing violent video games increases the frequency of aggressive behavior in children. The independent variable in this study is the type of video game played. The dependent variable in this study is the amount of aggressive behavior exhibited by the children. An experimenter wants to determine the relationship between rehearsal.repetition of a list of definitions of difficult SAT vocabulary words and later recall of these definitions. The independent variable in this study is the amount of rehearsal/repetition. The dependent variable in this study is the number of correctly recalled definitions. An experimenter wants to determine if a new drug reduces hyperactivity in children. The independent variable in this study is the drug. The dependent variable in this study is the level of hyperactivity. An experimenter wants to determine the effects of cell phone use on driving safety. Participants were randomly assigned to either drive an automobile simulator while talking to a friend on a cell phone, or to drive a simulator without talking on a cell phone. The independent variable in this study is cell phone use. The dependent variable is driving safety. Operational Definitions An operational definition is a precise description of how the variable in a study will be manipulated and measured. Precise definitions of variables, terms, and concepts facilitate future repetition of the study. For example, in a study measuring the relationship between rehearsal/repetition and recall of difficult SAT vocabulary words, rehearsal might by operationally defined as the number of times the subject reads aloud a list of words. The difficult words might be operationally defined as answers to Level 3 Vocabulary-in-Context questions. The recall might be operationally defined as the percentage of words that are correctly defined.
Descriptive Research Surveys
A research technique that uses questionnaires or interviews, or a combination of the two, to assess the behavior, attitudes, and opinions of a large number of people. The entire group that a researcher wants to study is called a population. Researchers generally question only a sample of the population whose opinions they seek to assess. A random sample, in which every person in the population has an equal chance of participating, helps minimize bias and ensure that the sample is representative. It is important to note that survey respondents often report that they are healthier, happier, and less prejudiced than would be expected based upon the results of other types of research. This phenomenon is known as the social desirability bias.
The Experimental Method Definition
An experiment is a carefully controlled method of investigation used to establish a cause-and-effect relationship. The experimenter purposely manipulates and controls selected variables in order to determine cause and effect.
Correlation Studies Correlation And Causation
Correlation studies indicate the possibility of a cause-and-effect relationship. It is very important to remember that correlation does not prove causation. For example, research studies have found a moderate correlation of +0.4 between SAT scores and college grades. However, this correlation does not tell us whether high SAT scores cause high college grades. Other known and unknown factors such as the level of achievement motivation and the pressure or absence of tutors could be responsibly for both the SAT scores and the college grades.
The Experimental Method Disadvantages Of Experiments
Create artificial laboratory conditions that do not correspond to real-life situations. Can be compromised by confounding variables that are difficult to identify and control. Susceptible to researcher and participant biases. Raise ethical concerns when subjects are deceived.
Descriptive Studies Measures Of Variation
Definition A measure of variation is a single score that presents information about the spread of scores in a distribution. Range The highest score in a distribution minus the lowest score. Standard deviation The most widely used measure of variation. A standard measurement of how much the scores ina distribution deviate from the mean. Normal distribution Normal distributions form a bell-shaped or symmetrical curve. In a normal distribution of test scores the percentage of scores that fall at or above the mean score is 50. The percentage of test scores that fall at or below the mean score is also 50. In a normal distribution, approximately one-third of the scores fall one standard deviation below the mean and one-third of the scores fall one standard deviation above the mean. For example, the Wechsler IQ tests have a mean of 100 and a standard deviation of 15. This means that one-third of the people taking theses tests will have scores between 85 and 100, and another third will have scores between 100 and 115. All score-based normal curves have the following 68-95-99.7 rule in common Approximately 68% of all scores fall within one standard deviation of the mean. Approximately 95% of all scores fall within two standard deviations of the mean. Approximately 99.7% of all scores fall within three standard deviations of the mean.
Descriptive Research Definition
Descriptive research includes methods that enable researches to observe and describe behaviors and mental processes without manipulating variables. Descriptive methods do not enable researchers to establish cause-and-effect relationships.
The Experimental Method Advantages Of Experiments
Enable researchers to identify cause-and-effect relationships. Enable researchers to distinguish between real and placebo effects. Enable researchers to control bias by using a double-blind study. Enable researchers to manipulate the independent variable and measure the dependent variable. Enable researchers to replicate a study, thus increasing confidence that the independent variable influences the dependent variable.
Descriptive Studies Measures Of Central Tendency
Measures of central tendency describe the average or most typical scores for a set of research data or distribution. Measures of central tendency include the mean, median, and mode. Mean The sum of a set of scores in a distribution divided by the number of scores. The mean is the average score. Extreme scores have a greater impact on the mean than on the mode or the median. Any chance in the highest score in any distribution must result in a change in the mean. Median The score that divides a frequency distribution exactly in half, so that the same number of scores lie on each side of it. The median is a better measure of central tendency when extreme scores distort the mean. Mode The most frequently occurring score in a distribution. An Example The nine members of a psychology class earned the following scores on a 10-question quiz: 3, 5, 5, 5, 6, 7, 8, 10, and 10 The mean score is a 6.5, the median score is a 6, and the m ode is 5.
Descriptive Research Meta-Analysis
Meta-analysis is a procedure for statistically combining the results of many different research studies. For example, many social scientists have investigated the relationship between extroversion and sales success. A comprehensive meta-analysis of thirty-five separate studies enabled researches to analyze data for 3,806 salespeople.
Inferential Statistics Key Points
Most experiments are conducted with a small sample of subjects. Psychologists want to generalize the results from their small sample to a larger population. Inferential statistics are used to determine how likely it is that a study's outcome is due to chance and whether the outcome can be legitimately generalized to the larger population from which the sample was selected.
Ethical Guidelines Animal Research Studies
Must have a clear scientific purpose. Most provide humane living conditions for animal subjects. Must legally acquire animal subjects from accredited companies. Must minimize the amount of suffering. It is important that less than 10 percent of research is done with nonhuman animals. Ninety percent of the nonhuman animals are rats, mice, and pigeons.
Descriptive Studies Skewed Distributions
Positively skewed distributions A positively skewed distribution contains a preponderance of scores on the low end of the scale. The mean will be higher than the median in a positively skewed distribution. The median is thus a better representation of central tendency than the mean in a positively skewed distribution. Negatively skewed distributions A negatively skewed distribution contains a preponderance of scores on the high end of the scale. The mean will be lower than the median in a negatively skewed distribution. The median is thus a better representative of central tendency than the mean ina negatively skewed distribution.
The Experimental Method Experimental Controls
Purpose Controls are used to ensure that all groups in the experiment are treated exactly the same, except for the independent variable. Problems Experimenter bias—occurs when a researcher's expectations or preferences about the outcome of study influence the results in a hoped-for direction. Sample bias—occurs when research participants are not representative of the larger population. For example, a researcher wanted to study the behavior of neighborhood trick-or-treaters who appeared at her home on Halloween night. The researcher cannot generalize her findings to all children since she used a biased sample limited to her own neighborhood. Solutions Random assignment—procedure by which participants are assigned to experimental and control groups by chance. This minimizes pre-existing differences between participants assigned to the different groups. Random assignment thus reduces the effects of confounding variables. Placebo—an inactive substance or fake treatment often used as a control technique in drug research. It allows researchers to separate the effects of the drug from the expectations of the participants. Single-blind study—a procedure in which the subjects do not know whether they are in the experiment or control group. Double-blind study—a procedure in which neither the researcher nor the participant knows which group received the experimental treatment. This procedure reduces experimental bias. The single-blind technique is more appropriate than a double-blind technique when a variable such as race or gender makes blinding impossible.
Inferential Statistics Statistical Significance And The p-Value
Results are statistically significant when the probability that the findings are due to chance is very low. For example, if the difference between the mean scores of two groups is statistically significant, a researcher would conclude that the difference most likely exists in the population of interest. If the difference is not statistically significant, ar researcher would conclude that the difference occurred by chance. The p-value is the probability of concluding that a difference exists when in fact this difference does not exist. By consensus, a statistically significant difference is one that would occur only 5 percent of the time or less. The smaller the p-value the more significant the results. A p-value can never equal 0 because researchers can never be 100 percent certain that the results did not occur by chance.
The Experimental Method Participants: Experimental And Control Groups
The experimental group compromise the participants who are exposed to the independent variable. The control group comprises the participants who are exposed to all experimental conditions except the independent variable. This enables the experimenter to make comparisons with the experimental group. Confounding variables In a controlled experiment, confounding variables are differences between the experimental group and the control group other than the independent variable. Confounding variables such as gender, age, and education can have an unwanted influence on the outcome of an experiment. For example, in a study measuring the impact of playing violent video games on the frequency of aggression in children, confounding variables could include the income level of the children's parents and the incidence of child abuse.
Descriptive Research Studies Of Development
The longitudinal method measure a single individual or group of individuals over an extended period of time. For example, a longitudinal study of intelligence would retest the same people over a period of years. Longitudinal studies provide in-depth information but can be expensive and time-consuming. In addition, participants who drop out during the course of the study may be different in important ways from those who did not drop out. The cross-sectional method compares individuals of various ages at one point in time. For example, a cross-sectional study fo achievement motivation would test eighth, tenth, and twelfth grade students at the beginning of the school year. Cross-sectional studies provide information about age differences. However, it is very difficult to make generalizations since cross-sectional studies measure behavior at only one point in time.
Correlation Studies Advantages Of Correlation Studies
They can be used to describe or clarify a relationship between two variables. They can be an efficient way to utilize pre-existing data. They can be used to dispel illusory correlations. Although widely believed, an illusory correlation is in fact non-existent. For example, it is widely but erroneously believed that there is a correlation between date of birth and personality traits.
Correlation Studies Disadvantages Of Correlation Studies
They cannot be used to establish cause-and-effect relationships. They cannot be used to establish the direction of causal influence. They do not allow researches to actively manipulate the variables. They make it difficult to identify the impact of confounding variables.