Questions: 1. Compare and contrast internal and external validity. Describe and give examples of research questions for which external validity is a primary concern. Describe and give examples of...

Questions:
1. Compare and contrast internal and external validity. Describe and give examples of research
questions for which external validity is a primary concern. Describe and give examples of
research questions in which internal validity is a primary concern. Discuss strategies researchers
use in order to make strong claims about the applicability of their findings to a target population.

Internal validity is dealt with the accuracy of the results. If samples are not selected randomly, this
affects the accuracy of the results. One of the examples where internal validity can be applicable is to
find a causal relationship between two variables from the study. A study is said to have internal validity
if the results indicate that the changes in the dependent variable is due to the predictor variable which
may be manipulated.
External validity is dealt with the generalization of what is found to the population. If the sample
selected from a specific section of the population, then it should not generalize the results to the entire
population. External validity involves in the study's ability to generalize the results across different
situations, groups of people, or experimental procedures.
So, internal validity measures the accuracy of resulys, while external validity relates the useful findings
are for many samples, or procedures. The study design should be to achieve good internal and external
validity.
An example of research experiment with high internal validity is the experimental studies performed by
a medical researcher where the finding the cause of a disease, which has many symptoms.
2. Compare and contrast random selection and random assignment. Be sure to include a
discussion of when you would want to do one or the other and the possible consequences of
failing to do random selection or random assignment in particular situations.

Random selection is about to draw the sample for a study from a population. Random assignment is
about to assign the sample that are drawn from different groups or treatments in the study.
Both random selection and assignment can be applied in a study. A random sample of 200 students
from a population list of 1000 students is an example of random sampling. Now, randomly assign 100 of
these selected students to get some new additional treatment and the other...