| Tag | Value |
|---|---|
| file | Inferential_Statistics_eur-inferential_statistics-213-en_eur-inferential_statistics-213-en |
| name | eur-inferential_statistics-213-en |
| section | Inferential Statistics/Regression/Dummies, Inferential Statistics/Regression/Simple linear regression, Inferential Statistics/Regression/Equation |
| type | schoice |
| solution | FALSE, FALSE, FALSE, TRUE |
| Type | Interpreting output |
| Program | |
| Language | English |
| Level | Statistical Literacy |
A researcher wants to compare four groups (group 0, 1, 2 and 3) with respect to their average high school grade. However, she has only regression analysis at hand, and therefore she transforms the variable “group” into dummy variables. Group 0 has a score of 0 on each of the dummy variables. She gets the following output:
| Group | B | Std.Error | Beta | t | Sig |
|---|---|---|---|---|---|
| (Constant) | 3.75 | 0.758 | 4.945 | 0.001 | |
| Group 1 | 3.5 | 1.072 | 0.691 | 3.264 | 0.009 |
| Group 2 | 2.75 | 1.072 | 0.543 | 2.564 | 0.028 |
| Group 3 | 2.5 | 1.313 | 0.38 | 1.904 | 0.061 |
Which of the following statements about the group means is correct?
The correct answer is that group 0 and 1 differ. Group 0 is your reference group; the unstandardized B coefficients show the difference in means between one of the three groups and group 0. When looking at group 1, you can see that the B coefficient is 3.5, which signifies a mean difference of 3.5; this difference is significant at p < .05.
The B of 3.75 here refers to the mean of the reference group, which is group 0. Furthermore, there is no linear decrease in means from groups 0 to 3, nor does group 3 have the lowest mean. Instead, group 0 has the lowest mean, followed by group 3, then group 2. Group 1 has the highest mean.