Missing the Forest for the Trees

I just completed grading your "comparison" homework and have posted the grades.

There is a figure of speech called "missing the forest for the trees." This means that one can get caught up in the details of a problem without really understanding the real issues that are involved.

An example of "missing the forest for the trees" is your homework.

• Why do we reexpress data?

We reexpress to equalize the spreads between batches.

• But why do we care about equalizing spreads?

We care about equalizing spreads since we wish to make a simple comparison between batches.

• What is a simple comparison?

A simple comparison is saying that one batch is, say, 5 units large than another batch.

If you don't conclude your analysis with a simple comparison, then all of your work (finding 5-number summaries, constructing a spread vs level plot, reexpressing, etc) is for NOTHING.

In other words, MAKING A USEFUL INTERPRETATION (in this case, a useful comparison) is EVERYTHING.

A few of you were successful in making simple comparisons in your homework and I congratulate you if you got a 30/30 on the comparing batches homework.

Remember, don't forget to look for the forest.