Experimental Design

Making a causal conclusion possible.

12 problems · about 21 minutes · VAR-3.C, VAR-3.E

NameDate

Figure — use these to answer the problems

Treatment against control. The gap is the evidence, and it means nothing without the control bar.

Treatment14

Control8

Treatment improved14

Control improved8

Figure 1

Straightforward practice. Get the method working first.

5 problems

Grouping similar subjects before randomising within each group is called what? 1 blocking, 2 blinding.
Answer
2
Why does random assignment permit a causal conclusion?
- It balances every other difference, known and unknown, across the groups.
- It is fairer to the subjects.
A group receiving a fake treatment is called what? 1 control, 2 treatment.
Answer
Grouping similar subjects before randomising is called what? 1 blocking, 2 blinding.
Answer
Does blocking raise power? 1 yes, 0 no.
Answer

The same ideas with more to keep track of.

3 problems

Can an observational study alone establish causation? 1 yes, 0 no.
Answer
A variable changing alongside the treatment is called what? 1 confounding, 2 blocking.
Answer
How many principles of design were listed?
Answer

Mixed problems. Work out what kind of question it is before you start.

4 problems

9
Which features belong to a well-designed experiment?
- Random assignment to treatments
- A control group
- Enough subjects per group
- Letting subjects choose their group
- Tick every box that applies.
Subjects improve from believing they were treated. Placebo effect? 1 yes, 0 no.
Answer
The Licence
What licenses a causal conclusion? 1 random assignment, 2 a large sample.
Answer
The Blinding
Neither subjects nor measurers know the groups. Double blind? 1 yes, 0 no.
Answer