The 1st sentence of the Introduction
The first sentence of the Introduction is a tricky thing to write.
It is tricky because when readers see it, they form expectations about all that will follow. For instance, take a look at this first sentence:
"Spiral treatment effects have long been used in the study of epidemiology."
When you read this, what do you expect the paper to be about?
Well, "spiral treatment effects," for a start. Many readers also sense a "but" lurking in the offing: they have been widely used BUT....
Here is another one:
"In the classic QRT problem, agents make one draw from an unknown distribution in each period."
What do you expect this paper to be about? Here, too, most readers, expect a "but" to follow. The "but" could relate to the type of problem (classic QRT or another one), how the agent goes about making draws, or any other aspect of the sentence. Certainly, the expectation is that some idea in this sentence will be crucially relevant for the paper. It's a problem when that isn't true.
Now, here are some types of first sentences you want to be wary of:
Adam Smith wrote...
The EITC is the largest ...
The recession has brought....
This paper studies a 2007 policy in Nicaragua that...
Consider the expectations each of these sentences creates in the reader's mind: are they too high, too low, off topic, or otherwise inaccurate?
You can learn more about how to write introductions in our introductory textbook.
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