What are pitfalls of observational studies?
A: It might result ethical issue
B: it is difficult to ensure a valid counterfactual
C: we might not think of all the control variables
D: some variables are very hard to measure
A: It might result ethical issue
B: it is difficult to ensure a valid counterfactual
C: we might not think of all the control variables
D: some variables are very hard to measure
举一反三
- 【多选题】What does “Market Segmentation” include? A: Geographic variables B: Demographic variables C: Psychographic variables D: Product-use variables
- I think it _______ more and more difficult for small shops to survive. A: will might be B: might will be C: definitely be D: will definitely be
- ____ we is known to all, English is not very difficult to learn. A: What B: As C: That D: Which
- What might we connect a perfume with?
- –What do you think the noise was? –It (__) a cat. A: may be B: might be C: could have been D: might have been