Jared is conducting an experiment with extrasensory perception (ESP) training. He begins with a pretest of his 40 participants and then divides them into two groups based on their scores. The participants with the 10 lowest scores are given extensive training on how to detect the signals. The participants with the 30 highest scores are given no training. Both groups are retested and the average score of the participants with the training improved, whereas the average score of the participants without the training fell. Which threat to internal validity should Jared consider?

In some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. the production of sterile male ligers is an example of read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. the production of sterile male ligers is an example of a postzygotic barrier the founder effect sympatric speciation a prezygotic barrier

You're doing research for a public essay on alternative medicine. which of the following sources has the most reliable information? a. a post on a social networking site about the undesired side-effects of different alternative medicinesb. a recent government report comparing the results of alternative and contemporary medicine for a specified diseasec. an anonymous article on a medical website that claims the success of alternative medicined. a 2003 study conducted by a medical research center about the effects of alternative medicine

"all the characteristics and experiences that define each of us as individuals" is the definition of