If you plot the test information, this will show how much information there is at any given point of your latent trait scale, and the target value, where the test information if maximized. TIF is also an inverse function of standard error of measurement, so where you have most information, you also have the least error. If you also plot the persons' scores on the latent trait, you can see whether most of your persons are in a range on the latent trait with a lot or a little information.
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