Two researchers are analysing the same dataset, using multiple regression analyses predicting a DV from IV1 and IV2. Researcher Afinds that IV1 is a significant predictor, and Researcher 2 finds that IV1 is not a significant predictor. Assuming moderately inter-correlated independent variables, which of the following differences in analysis strategy could explain their results?

1. Researcher A used a hierarchical multiple regression with IV2 in Block 1 and IV1 in Block 2. Researcher B used a hierarchical multiple regression with IV1 in Block 1 and IV2 in Block 2.
2. Researcher A used a standard multiple regression. Researcher B used a hierarchical multiple regression with IV1 in Block 1 and IV2 in Block 2.
3. None of the above could explain the difference in results.
4. Researcher A used a hierarchical multiple regression with IV1 in Block 1 and IV2 in Block 2. Researcher B used a standard multiple regression.