Lecture Communication research: Asking questions, finding answers (2/e): Chapter 11 - Joann Keyton

Chapter 11 Testing for Differences Differences betweens groups or categories of the independent variable Statistical tests of difference reveal whether the differences observed are greater than differences that might occur by chance – Chi-square – t-test – ANOVA 1 © 2006 by The McGraw­Hill Companies, Inc. All rights reserved. Inferential Statistics Statistical test used to evaluate hypotheses and research questions Results of the sample assumed to hold true for the population if participants are – Normally distributed on the dependent variable – Randomly assigned to categories of the IV Caveats of application 2 © 2006 by The McGraw­Hill Companies, Inc. All rights reserved. Alternative and Null Hypotheses Inferential statistics test the likelihood that the alternative hypothesis is true and the null hypothesis is not Significance level of .05 is generally the criterion for this decision – If p .05, then alternative hypothesis accepted – If p > .05, then null hypothesis is retained 3 © 2006 by The McGraw­Hill Companies, Inc. All rights reserved. Degrees of Freedom Represented by df Specifies how many values vary within a statistical test Collecting data always carries error df help account for this error Rules for calculating df for each statistical test 4 © 2006 by The McGraw­Hill Companies, Inc. All rights reserved. Four Analytical Steps 1. Statistical test determines if a difference exists 2. Examine results to determine if the difference found is the one predicted 3. Is the difference significant? 4. Evaluate the process and procedures of collecting data 5 © 2006 by The McGraw­Hill Companies, Inc. All rights reserved. ... - tailieumienphi.vn