Interpreting Figures - AAMC Sample Test

[663697]

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To my knowledge, the stars represent statistically significant findings. If the question had asked, "which situation had the highest FL activity?", would it be incorrect to choose AAG, wild-type since it isn't labelled as significant? Would AAA, yqeV be correct instead?

 

[aldol16]

You can't tell which has the highest activity because the error bars of the two black columns overlap. Those values look to be statistically indistinguishable so no one condition gives you the highest activity. You could only say that both AAA and AAG in the WT condition give you the highest activities.

Stars mean statistical significance for a specific comparison. In other words, the stars here are comparing the WT with the mutants within AAA or AAG. In other words, they don't mean that mutant AAA and mutant AAG are statistically different from each other - they very well may be but that wasn't the statistical question that was asked.

 

[663697]

You can't tell which has the highest activity because the error bars of the two black columns overlap. Those values look to be statistically indistinguishable so no one condition gives you the highest activity. You could only say that both AAA and AAG in the WT condition give you the highest activities.

Stars mean statistical significance for a specific comparison. In other words, the stars here are comparing the WT with the mutants within AAA or AAG. In other words, they don't mean that mutant AAA and mutant AAG are statistically different from each other - they very well may be but that wasn't the statistical question that was asked.

So, for example, that there is a significant difference in FL levels for mutant AAA and WT AAA? In that case, why aren't there stars for the WT bars? Does the star on the mutant bar already imply the significant difference between them, making the use of a second star on the WT bar redundant?

 

[aldol16]

So, for example, that there is a significant difference in FL levels for mutant AAA and WT AAA? In that case, why aren't there stars for the WT bars? Does the star on the mutant bar already imply the significant difference between them, making the use of a second star on the WT bar redundant?

Well, the comparison should always be included in the legend. The authors should tell you which comparison the star corresponds to. Here, it appears that the star signifies that the mutant AAA is different from the wild type AAA and the same for AAG. If you already have a star above the mutant, it is redundant and confusing to have another star above the WT as well (because in that case, there would be stars above each bar here!). It's like saying "Tom is Sally's husband" and "Sally is Tom's wife." You only need to say one of those to get your meaning across - saying the other as well is redundant.

 

[663697]

You can't tell which has the highest activity because the error bars of the two black columns overlap. Those values look to be statistically indistinguishable so no one condition gives you the highest activity. You could only say that both AAA and AAG in the WT condition give you the highest activities.

Stars mean statistical significance for a specific comparison. In other words, the stars here are comparing the WT with the mutants within AAA or AAG. In other words, they don't mean that mutant AAA and mutant AAG are statistically different from each other - they very well may be but that wasn't the statistical question that was asked.

One more question -- if the error bars of the two WT bars didn't overlap, would it be enough to conclude that one was greater than the other?

 

[aldol16]

One more question -- if the error bars of the two WT bars didn't overlap, would it be enough to conclude that one was greater than the other?

Yes, if the error bars clearly don't overlap, then one would be statistically different from the other.