In Yerkes’ study he compared the test results of different racial groups and so the races of the participants will have been taken down.
(ii) Valid
--The alpha test contained many of the types of questions that are in modern day IQ test; this means that they must be useful in testing a literate person. This shows that the results of the recruits who took the alpha test should be valid because they must be testing actual IQ.
--The results of the recruits who were: literate and took the alpha test, illiterate and took the beta and who failed and were given an interview, should all be valid because they would have been able to complete the test and for the most part it would have tested their IQ.
Invalid
Questions
--There was a cultural bias in both the alpha and beta tests, this decreased the validity of the tests because it meant that they weren’t testing IQ, but instead they were testing the cultural knowledge of the recruits.
The types of questions that were in the alpha test included:
- Christy Matthewson is famous as a: writer, artist, baseball player, comedian.
- Crisco is a: patent medicine, disinfectant, toothpaste, food product.
All of which need a general knowledge of 1900s American culture.
--The beta test contained picture questions like putting the filament on a light bulb and he strings on a violin. The immigrants may not even know what a bulb looks like and had never seen a violin. This may have also caused a problem to the poorly educated black recruits.
Methodology
--Illiterate recruits were often sent to do the alpha test, even though it was known that they couldn’t read or write. This was because the numbers of literate people were overestimated by Yerkes and so, the officers at the bases just sent some of the recruits to do the alpha test, reducing the number of recruits taking the beta test. This means that although the results are valid for the recruits who actually did take the beta test, the results of the ones that were switched definitely aren’t valid.
--Some of the recruits couldn’t use a pencil and had possibly never even seen one before; this means that couldn’t even complete the beta test.
--The conditions in which the tests were given were usually very poor; most didn’t have the full time to do the test. The atmosphere must also have been off-putting for those recruits who didn’t speak English, they were put in a room to do a test, in which all the instructions are given in English and they may not know how to use a pencil.
(iii) In order to improve the validity of the Yerkes’ IQ tests the questions need to be greatly improved. The possibility of failure because of lack of cultural knowledge has to be removed.
Alpha Questions could include:
-
Black is to white as vertical is to: Horizontal
-
Are digits 08232569 are the same as 96523208 read backwards. No
Beta questions could include choosing which piece of the puzzle fits the space. Or a next shape in the sequence e.g.
Which is the next shape?
These changes should increase the validity of the results because they will actually be testing IQ and not just the cultural knowledge of the participants. It should also be easier for the beta questions to be filled in by illiterate participants and immigrants, increasing the validity of their results.
