Authors Arx, Lemola, and Garb conducted an experiment to see if different intelligence tests would yield similar results for children. They base their assumptions off previous research that suggests that most standardized tests measure similar underlying concepts which makes them all valid. They do note however, that some tests require different skills such as object manipulation or a greater focus on literacy. Despite this, results should generally be similar. The experiment conducted was taking 5 standardized German intelligence tests and administering each to a set of 206 typically developing children (that is, children without any notable disabilities or impairments) and record the results to see if there were any major discrepancies. Each test focused on slightly different forms of intelligences. The children chosen were between the ages of 6-11 and the tests were administered within public schools in a quiet room. Participants were given tests every 1-97 days in order to see if the time taken between tests would be a significant factor in their scores. The time allocated for each test varied based on the standardized guidelines for that particular test. Data and test scores were compared to each other to determine whether their hypothesis was correct. Their results show that students tended to perform better on older tests than newly standardized ones and that composite test scores correlated with each other. Results also show that most students performed similarly on different tests. The authors determined that the biggest factor affecting student performance were simply common or meaningless errors or mistakes such as retrieval error even when the student(s) knew the information. There was no strong correlation in changing the time between tests. Furthermore, factors such as country of origin and mother tongue affected results. Some tests were also better at measuring comparability for students who were gifted or slow. The more recent tests were better indicators and provided better information on gifted and slow students. Some tests were better for certain students because they required less focus on knowing the spoken/dominate language so cultural differences were better accounted for. Tests that had a higher focus on using the dominant language made it slightly more difficult on students who were not from the country of origin or who had less experience with that language. The authors conclude that no single IQ test should be utilized and that it is better to use at least 2 and compare the results before making a final decision on the child’s abilities. They believe that using only 1 test may not provide enough detail on the child’s abilities and that multiple factors can affect them as discussed above.