PSYC 320 Lecture Notes - Lecture 15: City Homicide, Dependent And Independent Variables, Physical Attractiveness

• School: American River College
• Department: Psychology
• Course: PSYC 320
• Professor: Mitchell

Document Summary

Correlation coefficient: describes the degree of relationship between two variables. Ranges from r = +1 to -1. Positive: as one variable increases, the other increases; one decreases, the other decreases. Negative correlation: move together, but opposite directions. Strength of the relationship closeness to +1. 00/-1. 00, not by the sign (+/-) Which indicates a stronger correlation: -. 74 or +. 21 (-. 74) Look at the absolute value of the correlation coefficient to determine its strength. Weaknesses: you cannot prove causation with a correlation. 3rd variable problem: there is a strong positive correlation between the amount of ice cream consumption and city homicide rates. On the days that the most ice cream is consumed, there are the most murder committed. Manipulate only one variable at a time. All other variables are held constant or eliminated. Operational definitions be able to define each variable clearly and precisely. Before we can measure a variable, we need to know exactly what it is.