Hundreds of coping strategies have been identified. Classification of these strategies into a broader architecture has not been agreed upon. Researchers try to group coping responses rationally, empirically by factor analysis, or through a blend of both techniques.:751 In the early days, Folkman and Lazarus split the coping strategies into four groups, namely problem-focused, emotion-focused, support-seeking, and meaning-making coping.:303 Other research, like Weiten, for instance, identifies four types of coping strategies:, like Appraisal-focused (adaptive cognitive), Problem-focused (adaptive behavioral), Emotion-focused, Occupation-focused coping. Billings and Moos added avoidance coping as one of the emotion-focused coping. Some scholar questioned the psychometric validity of forced categorisation as those strategies are not independent to each other.:753 Besides, in reality, people can adopt multiple coping strategies simultaneously.