The question whether different intelligence tests veer different results is definitely a valuable interrogation. As shown through the five German standardized tests, the intelligence tests all focus on something different. The RIAS has two verbal and two non verbal components, the SON-R 6-40 is a completely non verbal test, and the CFT 20-R is also non verbal focusing on fluid intelligence. Moreover, the WISC-IV test focuses on verbal comprehension, perceptual reasoning, working memory, and processing speed and the IDS tests six different developmental domains, cognition, psychomotor skills, social-emotional competence, language, mathematics, and achievement motivation. Therefore, questioning if taking different tests would result in different intelligence scores is valuable.
The study used 206 participants, consisting of 51% girls, 49% boys, which is definitely a fair division because discrepancy between gender difference is averaged out. Furthermore, the participants were all aged 6-11 years in primary schools in German speaking parts of Switzerland. However, the geography of where this study was conducted causes a language issue when taking the tests. Since the question in hand is whether different intelligence tests could result in different intelligence scores, the fact that the different tests differ in how they are administered means that some responses could be verbal or nonverbal. The study shows that it is an issue for the test takers with a different country of origin or different mother tongue taking tests in German. Due to the slight language barrier for some of the participants, the experimental steps were not exactly neutral. On the other hand, the fact that five different tests were selected, among those texts having different skills and components being tested in different ways, was a great way of collecting data because it provided a mean of general intelligence rather than concentrated in one specified area.
The study asked whether difference intelligence tests yield different intelligence scores. The results proved that, although results were consistent, some mean test scores were slightly higher for the IDS and that scores were slightly lower for the RIAS and SON-R 6-40. The IDS, WISC-IV, and CFT 20-R had no significant differences in scores. When analyzing the actual administration of the tests, the test procedures accounted for 4% of the reason for variance of intelligence scores. Most of the variance was actually due to unspecific errors (30-42%). These errors are meaningless and are often things that the children knew but mistook. In conclusion, different intelligence tests still rule out the same outcome for intelligence scores. The more tests taken however, in this case five, simply averages out the the unspecific errors and the mean of the scores is what represents the ultimate intelligence score. The study explains that no single IQ test should be used to test a child’s intelligence. At least two tests should be taken and results compared. Using one test may not provide enough detail as shown that different tests can examine multiple factors or focus on few, for this example specifically, if all intelligence tests were strictly verbal, some students would have more difficulty because of language rather than because of their ability.