Dr. olson is studying the importance of privacy to people of different ages. in a cross-sectional study, she finds that people in their sixties are more reluctant to reveal personal information than are college students. what is the best conclusion?

A possible conclusion is that older people (in this case, people in their sixties) care more about their privacy than younger people. However, two important things need to be noted in this experiment:

1. This conclusion does not provide an explanation as to why this might be the case. We would need more information if we want to develop a theory that provides reasons for this situation to happen.

2. There might be other factors we have not study that might alter our conclusion. So it could only be a hypothesis until we have more information to rule other possibilities out.

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)