Estimated gender gap is 9.01 (p<0.01) points and it is statistically significant. On average, boys are correctly identifying 9 letters more than within schools. Remove gender from the model. Suppose you are interested in whether there is a difference in mean letter recognition for schools with one shift versus two shifts. Fit the model two ways with shift uncentered and shift grand mean centered. Is – there a statistically significant difference in mean letter recognition for schools with one shift versus two shifts? Level-1 Model = + S1Q3_PPij rij β0j Level-2 Model = + + u0j β0j γ00 γ01*(Q205j) Model = + + S1Q3_PPij γ00 u0j+ rij Yes there is a statistically difference in mean number of letters correct for schools with one – shift or two. On average, the mean for schools with two shifts is 4.77 points lower than schools with one shift (p<0.05). What differs across the two models in terms fixed effects and variance components? Explain. The only difference is the intercept. This is because when shift is entered uncentered, the intercept is the mean for schools with one shift whereas when shift is entered centered, it is the mean across schools adjusted for percent of schools in either shift. In your own datasets, choose an outcome of interest. Run the unconditional model as a starting point for future analyses. What is the unconditional ICC?
Estimated gender gap is 9.01 (p<0.01) points and it is statistically significant. On average, boys are correctly identifying 9 letters more than within schools. Remove gender from the model. Suppose you are interested in whether there is a difference in mean letter recognition for schools with one shift versus two shifts. Fit the model two ways – with shift uncentered and shift grand mean centered. Is there a statistically significant difference in mean letter recognition for schools with one shift versus two shifts? Level-1 Model S1Q3_PPij = β0j + rij Level-2 Model β0j = γ00 + γ01*(Q205j) + u0j Model S1Q3_PPij = γ00 + + u0j+ rij Yes – there is a statistically difference in mean number of letters correct for schools with one shift or two. On average, the mean for schools with two shifts is 4.77 points lower than schools with one shift (p<0.05). What differs across the two models in terms fixed effects and variance components? Explain. The only difference is the intercept. This is because when shift is entered uncentered, the intercept is the mean for schools with one shift whereas when shift is entered centered, it is the mean across schools adjusted for percent of schools in either shift. In your own datasets, choose an outcome of interest. Run the unconditional model as a starting point for future analyses. What is the unconditional ICC?
mlm_refresher_lab_solutions.docx