The National Health and Social Life Survey, conducted to gather information about the eating habits of U. S. adults between the ages of 18 and 59, is an example of , in that every member of the larger group has an equal chance of being selected for inclusion in the sample.

The answer is random selection.

Explanation:

Random selection refers to a process in which there is a representative sample that is used for a specific study. Random means that people that are involved in the sample are chosen by chance. Thus, there are the same probabilities for each person to be chosen.

A random selection is important to scientists because the scientist's purpose is to generalize his or her findings related to the whole population. However, the purpose is not testing the whole population. Thus, the scientist chooses a specific group of people and selects people at random.    

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the earth’s crust is broken into separate pieces called tectonic plates (fig. 7.14). recall that the crust is the solid, rocky, outer shell of the planet. it is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. both types of crust rest atop solid, upper mantle material. the upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar.

each tectonic plate is free-floating and can move independently. earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. the term fault is used to describe the boundary between tectonic plates. most of the earthquakes and volcanoes around the pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. other observable results of short-term plate movement include the gradual widening of the great rift lakes in eastern africa and the rising of the himalayan mountain range. the motion of plates can be described in four general patterns:

collision: when two continental plates are shoved together

subduction: when one plate plunges beneath another (fig. 7.15)

spreading: when two plates are pushed apart (fig. 7.15)

transform faulting: when two plates slide past each other (fig. 7.15)