Question

Suppose an experimental group is being taught letters of the alphabet as a treatment. At about the same time, the students are watching an educational program on television, from which they learn the names of the letters. What is the name of the threat that this problem illustrates?

Answer 1

Threats to internal validity focus on the relationship between independent and dependent variables. Experiment about the topic which focuses on one group but not for two groups...It is a pretest design for the treatment, it relates the comparison between the group and the comparison group.
Threats:
Maturation is the one group design and it is not a two-group design focus on change at the same rate...
statistical regression has a tendency for subjects based on high scores due to subsequent tests. when dependent variables do not provide proper results it moves to the mean, it is the validity of the test. this experiment involves in reading instruction, subject group due to poor pre-test make more benefit than who scores average and high on a pre-test.
selection is the two group design by random sampling, random assignment having an equal chance for treatment that groups are equal.
Experimental mortality: it is the more group design, it makes a difference between the group.
Testing also two group designs it focuses on both groups for the pre-test, not for the treatment...There will be the interaction between pre-test and treatment.
Instrumentation is a one gruop design it measure the dependent variables.
Design contamination: Investigator conclude about the subject they find design contamination by compare notes
Compensatory rivalry: Social competition make anticipated effects of the designed treatment level.
Resentful demoralization this group with less level service they feel resentment and demoralization it increases the magnitude with their performance to receive good service.
Threats to External validity:
It has interaction effects of testing make result with the untested population. Its effects in selection bias and experimental treatment may not be the case in groups randomly selected...
Interaction effects of testing happen if there is no pre-test...The interaction effects of selection bias make low achievement.
Reactive effects of experimental arrangement make effects and multiple treatment interference make reactive effects on the experiment and does not occur in the regular program.