Altius fl #2 BS #24

[akimhaneul]

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For this question, it makes sense that old mice should be the control. But why not young mice that are not treated at all? They did this in the passage, so why can't YC also be the answer?

Is the correct answer the better answer because controls are used to see if an effect happened after treatment?

 

[aldol16]

Controls have meaning only within a certain context and tell you a specific kind of information. In general, if you're administered a treatment to group B, you want to withhold that same treatment from group A in order to see if the effect on group B is due to the treatment. For this to work, you also need to hold all other variables from group B to group A constant so that you are isolating the variable you're trying to measure. This means feeding mice at the same time with the same diet in the same location, etc.

What purpose would comparing the response of the treated group of mice here to the drug serve? In other words, say you're looking for telomere length as a biomarker since telomere length generally decreases with aging. In your treated group of old mice, you see an average telomere length of 5 nm. Which other group would serve as the best comparison for this group? In other words, comparing to what other group would infuse that "5 nm" with actual comparative meaning?

 

[Altius Premier Tutor]

First, note that this is not the original study, but a follow-up question. The researchers were wondering "Hey, since ResV improves heart function, can we take OLD MICE and give them enough ResV to turn them into the functional equivalent of young mice?" So, they are going to give a ton of ResV to old mice. They will need OLD mice, NOT young mice, because they have to be sure that the outcomes of their experiment are the result of OLD MICE + ResV, not just some characteristic of OLD MICE themselves. If they used YOUNG mice as a control that wouldn't be a control at all, it would introduce a confounding variable. It wouldn't even work as an experiment because you'd have two variables changing at the same time: Young vs. Old AND ResV vs. No ResV.