Coding missing data

In the previous videos, we looked at how…to deal with unusual data, specifically with outliers.…In this video, we're going to look at some ways of dealing…with missing data, which can create just as big a problem with analyses.…Let's start by creating a small data set…that includes an NA value, for not available.…The problem is that it makes certain…calculations just impossible, it just won't do them.…So for instance if I take a data…set here, I write one and put it in a variable called x1, and it consists of…five values: 1, 2, 3, NA, and a 5. The four is missing.…

So if I enter that you'll see that it shows…up in the work space as having five numeric values.…And let's click on that and there they are.…What's interesting about it is, for…instance, the summary procedure works with it.…If I do a summary…of this variable, it gives me a minimum, a first…quartile, a median, a mean, a third quartile, a max.…And then it lists how many NA's there are in the distribution.…And there's one.…On the other hand, the function mean.…