PSYC250 Essays - Design Of Experiments, Experiments,

PSYC250 Case Study One 1. In Janet's final project, one of her ideas utilizes a correlational design. In a correlational design, there is research involved. These researches usually involve using observational, archival, or survey methods to test a hypothesis. There is at least two variables being looked at in a correlational design, and these variables are rarely manipulated. Instead, the variables are determined if there is a relationship between them. In saying a relationship, we are trying to determine the similarities or differences between the variables, and the way one variable can correlate or form a relationship with another (Brehm, Kassin, & Fein, p. 36). This relationship can be measured based on the direction and strength. Let us call the variables X and Y. When X increases and Y doesn't increase in values, we say there is no correlation or relationship between the two variables. If as X increases, Y increases also, we can fairly say there is a correlation or relationship between the two variables. The relationship is either negative or positive, depending on Y increasing or decreasing in value. If as X increases Y increases, there is positive correlation, and if as X increases Y decreases, there is negative correlation. The strength of the correlation indicates how strong the relationship is between the variables. The strength is calculated using a mathematical equation, but we won't get into that in this paper. The measurement is between ?1 and +1. The closer to ?1, the stronger the relationship, and the closer to +1, the stronger the relationship. When the correlational coefficient, or the number value associated with strength, i s closer to ?1, we say a strong negative correlation. When closer to +1, we say a strong positive correlation. When it is 0, there is no relationship (Brehm, Kassin, & Fein, pg. 36,37). It is always important to know there is no causation or cause and effect in a correlational design. In Janet's first design, it is clearly a correlational design being used. Janet utilizes two types of research methods, observation and self-report. She is observing the one variable, facial expression and scoring it on a scale of 1-5. Negative facial expression gets a low number and positive facial expression gets a high number. The questionnaire is the second variable. The person who Janet observed would be given a questionnaire and asked to rate their mood on a scale of 1-10. The lower the score, the more negative the mood, and the higher, the more positive of a mood. The correlational study Janet is trying to determine is between the variable facial expression and the other variable mood. The design is trying to form a relationship between facial expression and mood. The criteria of this design is clearly correlational, because of the relationship trying to be determined between the two variables, and the fact that there is no manipulation being done. Next, the second research design of Janet's uses the idea of an experimental design. In an experiment, the idea is to establish cause and effect between variables. The experimenter does through control and random assignment. Control means that the experimenter has control over all procedures being done. He/she has control over the variables, the participants, and maintaining uniformity. Random assignment is that participants have an equal chance of being exposed to the independent variable or dependent variable. Also, participants aren't chosen for the conditions of the experiment based on race, sex, behavioral characteristics, or personal characteristics (Brehm, Kassin, & Fein, p. 39). In an experiment there are two main types of variables, the independent and dependent. The independent variable is the variable that is causation. The IV is manipulated to see the effect. The dependent variable is the effect of the IV (Lecture, 1/24/00). Janet's second idea is an experiment trying to prove cause and effect. The cause is the Intro to Psychology students' mood and having to read passages about a funeral or birthday party. The effect is their facial expression being taped as they're reading the passages. The facial expression is being scored on the same scale as in the correlational design. The independent variable is the mood of the Intro to Psychology students being measured according to their facial expression as they're reading the different passages. The dependent