IBM® SPSS® Amos™ 28

The following lines are equivalent ways of specifying that the variables xxx and yyy may be correlated and that their covariance is to be estimated.

xxx <> yyy
xxx<>yyy
xxx yyy
xxx yyy ()

As those examples illustrate,

•"<>" is optional. "<>" is treated as a single symbol. "<" cannot appear by itself. Neither can ">". Also, "< >" (with an embedded space) is not recognized.

•Empty parentheses represent covariances that need to be estimated. These empty parentheses are optional.

•White space (spaces and tab characters) can be used anywhere to make the text easier to read, except that a line that begins with white space is treated as a continuation of the preceding line.

You can fix a covariance at a constant value, say 1 as in the following line.

xxx yyy (1)

And you can name a covariance. In the following line the covariance between xxx and yyy is given the name, alpha. If any another covariances are also called alpha, then the estimates of all the covariances called alpha will be constrained to be equal.

xxx yyy (alpha)