Workplace bullying (e.g., work-related harassment, persistent criticism, withholding key information, spreading rumors, intimidation) has been shown to have a negative psychological effect on victims, often leading the victim to quit or resign. In Human Resource Management Journal (Oct. 2008), researchers employed multiple regression to examine whether perceived organizational support (POS) would moderate the relationship between work-place bullying and victims' intention to leave the firm. The dependent variable in the analysis, intention to leave (y), was measured on a quantitative scale. The two key independent variables in the study were bullying (x1, measured on a quantitative scale) and perceived organizational support (measured qualitatively as "low," "neutral," or "high").
a. Set up the dummy variables required to represent POS in the regression model.
b. Write a model for E(y) as a function of bullying and POS that hypothesizes three parallel straight lines, one for each level of POS.
c. Write a model for E(y) as a function of bullying and POS that hypothesizes three nonparallel straight lines, one for each level of POS.
d. The researchers discovered that the effect of bullying on intention to leave was greater at the low level of POS than at the high level of POS. Which of the two models, parts b and c, support these findings?