Say is the average increase in shoe size for upper-class people compared to middle-class people: then the Wald test can be used to test whether is 0 (in which case social class has no association with shoe size) or non-zero (shoe size varies between social classes).
There are many different species of vultures and each has a different type of habitat. Turkey vultures are the most prominent of the New World vultures and can be found in Southern Canada, the Continental United States, Mexico, Central America and South America. These vultures live in small caves, beneath bushes, in hollowed out logs, and sometimes in abandoned structures.
The Turkey Vulture breeds throughout Texas, but the winter population is largely confined to east of a line running from Wichita Falls (Pulich 1988) south to Del Rio. It might be noted, however, that there are records for this bird in Big Bend National Park for every month of the year except January (Warner 1973).