Research and Statistics in Psychology Wadsworth, a division of Thomson Learning

What Makes Psychology a Science? w The methods it uses to ask its questions about behavior and mental processes. w The belief that results obtained from its scientific inquiry should be able to be repeated.

The Scientific Method w Theory-Long-standing explanation for a behavioral phenomenon, based on prior observations. w Hypothesis-prediction of what will happen in the experiment w Gather Data-Taking data from a sample regarding your question. w Data analysis-Determining what the data mean. w Communicate Results-presenting at a conference or publishing in a journal

Common Research Methods In Psychology w Case Study w Survey w Naturalistic Observation w Participant Observation w Test Methods w Correlation w Experimental Method

Case Study w Popularized by Sigmund Freud w Detailed history of a single individual w Usually used when an individual demonstrates a rare disorder or symptomatology w It is limited in that the findings cannot be generalized to a larger population, but it may provide direction for further research.

Survey w A common form of research that allows the gathering of large amounts of data in very large populations. w During the administration of a survey, an investigator must take care to obtain a representative sample of their population. w Questions must be clear, non-biased, and appropriately formatted to obtain meaningful data.

Survey w Surveys may be conducted in person, on the phone, on the computer, or through the mail. w Cannot draw causal conclusions from the results.

Naturalistic Observation w Formal record of observed events in a natural setting. The scientist making the observations must be unobserved by the subject. w What a scientist gains by placing the subject in their natural setting they may lose by losing control over extraneous variables. w The scientist doing naturalistic observation must also be very careful to not let their own beliefs about what should happen in the naturalistic setting affect the way they “see” the events unfolding.

Test Method w Standardized tests are administered to a population. (Example: the SAT’s and the ACT’s are standardized tests) w Tests must have high reliability (measures the same thing every time) and high validity (measures what you say it does) for the data obtained from them to be meaningful.

Correlation w Determines the relationship between two variables. w The relationship is defined by a number from -1.0 to +1.0 w The closer the number is to either -1.0 or +1.0 the stronger the relationship w The (-) and (+) identify the direction of the relationship. A (-) means that as one variable increases the other decreases. A (+) means that as one variable increases the other increases as well.

Correlations Continued w Correlations are generally viewed using a scatterplot. w Correlations never allow you to draw causal conclusions. One reason for this, is that there may be a third variable influencing both of the variables used in your correlation.

Experimental Method w This method can provide cause-and-effect conclusions. w This method involves the manipulation of an independent variable to determine how it affects a dependent variable. Independent-the variable that is manipulated Dependent-the variable that is measured to determine the effect of the independent variable

Experimental Method w This method makes use of control groups and experimental groups. Control Group-a group that receives the identical treatment as the experimental group except for the independent variable Experimental Group-a group that receives the manipulation of the independent variable

Descriptive Statistics w Used to summarize the data gathered in an experiment w Measures of central tendency Mean-the arithmetic average Median-the number that divides the ordered scores in half Mode-the most frequently occurring score

Descriptive Statistics w Measures of Variance Variance-a measure that reflects how similar all of the numbers in your group are Range-measure of variability that is obtained by subtracting the smallest score from the largest Standard Deviation-Square root of the variance important in determining the normal distribution

Normal Distributions w A bell-shaped distribution of the scores of an experiment where half of the scores fall above the mean and half of the scores fall below the mean w The peak of the curve is the mean w Specific percentages of scores will fall within set standard deviations from the mean example: 68% of the scores will fall within one standard deviation from the mean

Testing for Significance w A statistical comparison of a control group and an experimental group to determine if their measures on the dependent variable are significantly different. w If they are, it means the scientist can say with 95% confidence that the two groups are different because of the independent variable.