A researcher trains observers to complete checklists while observing children's behavior on the schoolyard during recess. Over the course of the study, observers become more reliable in their observations. Any effect of a treatment in this study might be confounded with an threat to internal validity.

Why do governments supply public goods and services instead of selling them to those people who use them

Awoman was found strangled in the basement of her home where she lived with her husband. the crime scene was processed and investigators left. the next day, the medical examiner reported that a scalloped, woven belt was used to strangle the victim. the police asked the husband to search the house again to look for such a belt and he agreed. a belt was found that matched marks on the victim. the man was arrested. his attorney made a motion that the belt be excluded from the evidence as he contended that the search was not legal. which statement is true? a. the belt should be excluded because the search was not legal. the police did not obtain a search warrant, as needed according to the fourth amendment to the u.s. constitution. b. the belt is admissible because the man gave his consent to the second search. c. the belt should be excluded because the search was not legal. the police did not obtain a search warrant, as need according to michigan v. tyler. d. the belt is admissible as evidence, according to mincey v. arizona.

Which of the following would a historian most likely study to find data