Green Tea You wonder whether green tea lowers cholesterol.
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Question

Green Tea You wonder whether green tea lowers cholesterol.

Explain how to use randomization in this experiment. How does randomization neutralize those variables that are not controlled?

Accepted Answer

Hello there. Today we are going to solve the following practice problem together. So first off, let us read the problem and highlight all the key pieces of information that we need to use in order to solve this problem. A researcher wants to test whether a new herbal supplement improves short-term memory. Describe how to use randomization in this experiment, and explain how randomization helps to eliminate uncontrolled differences between participants. OK, so it appears this for this particular prompt, we're ultimately trying to determine two final answers. We're asked to determine How to use randomization for this particular experiment, that's our first part of our answer, our first answer, and our second answer is to explain how randomization helps to eliminate uncontrolled differences between participants. And we're trying to describe how to use randomization on the particular experiment for this problem, which this particular experiment, we have a researcher who wants to test whether or not a new herbal supplement improves short-term memory. So keeping this in mind, our first step that we need to take in order to solve this problem is we need to define the treatment indicator. So, what does that mean? So we need to assign capital T subscript I is equal to 1 if the participant lowercase i, so once again T subscript i is equal to 1. And we need to note, once again we're defining the treatment indicator and we're assigning T subscript I is equal to 1. If participant I receives the herbal supplement, And T subscript I is equal to 0 otherwise. So once again, T subscript I, which I'll call TI for short, TI is equal to 1 if the participant I receives the herbal supplement, and T subscript I equals 0 otherwise, otherwise meaning they do not receive the herbal supplement. So, now at this point, we need to measure each participant's short-term memory score. So once again, their short-term memory score will be Y subscript IYI after the study. So I'll go call it YI for short. So why subscript I. So once again, we're going to measure each participant's short-term memory score YI after the study. OK. Our second step now is we need to recall and apply randomization. So we need to use simple randomization so each participant has an equal 1 half 50/50 chance of receiving the supplement or not. So half of them will receive the supplement, the other half will not. This ensures that assignments are made entirely by chance. OK, moving right along here. Our third step now is we need to recall how to use independence under randomization. So as we should recall, randomization makes the treatment assignment in Independent of preexisting factors such as age, memory ability, or lifestyle, and this means that these factors are not systematically related to who gets the supplement. So with that in mind, our 4th step now is we need to consider how we are going to achieve a balance. So as we should recall, based on our prior knowledge and applying it to this problem, on average, both groups, such as the treatment and the control are balanced in all participant character characteristics. So once again, On average, both groups, in this case the treatment and control, are balanced in all participant characteristics. Therefore, any differences in outcomes cannot be explained by uncontrolled variables. Moving on to step number 5, so for our 5th step, we need to recall at this at this stage, we need to compare outcomes. So as we should recall, we need to compute the difference in mean memory scores between groups. And if the supplement group performs better, we will attribute this difference to the effect of the supplement. So once again, if the supplement group performs better, we will attribute this difference to the effect of the herbal supplement. So, for our 6th and final step, we need to recall at this point we need to justify the inference. So once again, we need to recall and use randomization-based tests to check whether the observed difference is due to chance, and this, as a result, will provide a valid statistical basis for casual conclusions. So why does randomization help? So as we should recall, based on our previous studies on randomization, it helps to spread uncontrolled differences evenly between groups, making them comparable. Therefore, as a result, any average differences in outcomes can be confidently linked to the treatment itself. So, based on this information that we've collected together, our final answer will be as follows. So assign participants randomly equal chance of supplement or control, randomization balances uncontrolled differences, so outcome differences reflect the supplement's effect. And that's it. That is our final answer. Thank you so much for watching. Hopefully that helped, and I can't wait to see you in the next video. Bye.

Green Tea You wonder whether green tea lowers cholesterol.
Explain how to use randomization in this experiment. How does randomization neutralize those variables that are not controlled?

Key Concepts

Randomization in Experiments

Controlling Confounding Variables

Causal Inference in Experimental Design

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