Textbook Notes (369,097)
Canada (162,378)
York University (12,903)
Psychology (3,584)
PSYC 2030 (144)
Chapter 9

Chapter 9 - Correlational Research.docx

4 Pages

Course Code
PSYC 2030
Rebecca Jubis

This preview shows page 1. Sign up to view the full 4 pages of the document.
Chapter 9: Correlational Research Correlation and Regression – The Basics  A correlation exists when two variables are associated or related to each other in some fashion – in a positive correlation the relationship is such that a high score on one variable is associated with a high score on the second variable as well as a low score on one relates to a low score on the other – a negative correlation is an inverse relationship; high scores on one variable are associated with low scores on the second variable and vise versa.  Jon Stuart Mill’s Method of Concomitant Variation (correlation method) states that changes in the value of one variable are accompanied by predictable changes in a second variable. Positive and Negative Correlation  An example of a positive correlation is study time and grades; the more time you spend studying the better your grades will be – an example of a negative correlation is goofing- off time and grades (GPA); the more time you spend goofing-off the worse your grades will be.  The strength of a correlation is indicated by the size of a statistic called the correlation coefficient, which ranges from -1.00 for a perfect negative correlation, through 0.00 for no relationship, to +1.00 for a perfect positive correlation – the most common coefficient is the Pearson’s r, for data measured on an interval or ratio scale. Scatterplots  Scatterplots indicate the strength of a correlation as well as provides a visual representation of the relationship shown by a correlation. Coefficient of Determination – r 2  A better sense of how to interpret the meaning of a correlation is to use what is called the coefficient of determination (r ), which is found by squaring the Pearson’s r – hence the coefficient will always b2 a positive number, regardless of whether the correlation is positive or negative – r is defined as the portion of variability in one of the variables in the correlation that van be accounted for by the variability in the second variable. Regression Analysis – Making Predictions  A major feature of correlational research is that predictions about behaviour can be made when strong correlations exist; if you know that a statistically significant correlation exists between two variables, then knowing a score on one of the variables enables you to predict a score on the other – making predictions on the basis of correlational research is referred to as doing a regression analysis.  A regression line on a scatterplot is used for making predictions and is called a “best- fitting line” which provides the best possible way of summarizing the points on the scatterplot – the formula for the regression line is Y= a + bX – a is the place where the line crosses the Y-axis (the Y-intercept), b is the slope and X is a known value and Y is the value you are trying to predict.  Y is sometimes referred to as the criterion variable and X as the predictor variable – when making a prediction in a regression analysis, it is possible to establish a range of scores for the prediction (confidence interval), within which the true prediction would be likely to occur a high percentage of the time (95% or 99%). Interpreting Correlations Correlations and Causality  With correlational research, the “all else is held constant” feature is missing and this lack of control makes it impossible to conclude anything about cause and effect from a simple correlation – two ways in which interpretation problems can occur with correlations: i. Directiona
More Less
Unlock Document

Only page 1 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.