[Rasch] Logit scores

Jack Stenner jstenner at lexile.com
Thu Dec 22 01:56:48 EST 2005


Agustin and list:

The Lexile Framework for reading is now available in Spanish - El Systema Lexile. We have linked several best selling Spanish reading tests and the State of Texas adopted the El Systema Lexile this year. We are seeing an increasing interest in biliteracy in parts of the U.S. Obviously such a policy objective is well served by being able to measure reading ability in both languages in a common metric. It is precisely because it takes so much time and energy to get a community comfortable with what scale values on a new metric imply that the process of "unification" has proven to be so important in science. Rasch gave us the mathematics to separate the scale from the instrument. The human sciences have been slow to model the more mature sciences in this important advance.    Happy holidays to all!!!    Jack  




 

-----Original Message-----
From: rasch-bounces at acer.edu.au [mailto:rasch-bounces at acer.edu.au] On Behalf Of Agustin Tristan
Sent: Tuesday, December 20, 2005 3:41 PM
To: Lee, Wynne; Mike Linacre (RMT); Rama Guinda; -Rasch
Subject: RE: [Rasch] Logit scores

Hello. We have the same problem in Latin American Countries, where we use a traditional "scale" from 0-10, or 0-100. In these scales, it is common to say that a passing score is 6 or 7 (60% or 70%). In this scale a score of 5 (or 50%) is equivalent to fail, and if our test has a normal distribution centered on the scale, a mean of 50% confirms what the journalists in our countries say: "we're loosers". In 95 we worked changing the scores reported by the Ceneval in Mexico, we adopted a scale from 700 to 1300, the mean centered in 1000: Miracle! the journalists and other people believed that 1000 is something like 10 (or 100%) and some students even got better than that, and no one was below 700 (or 7 or 70%)! we are not loosers since then! At least the journalists stopped to publish those articles concerning mean scores.
In El Salvador we suggested a national scale going from 300 for first grade children, up to 2700 for undergraduate, following an idea similar to Lexiles, that permit to have a wide range scale.
In any case, I think we have to provide the with a user's manual, otherwise the interpretation may be erroneous for many people.
May I propose to have one day a general logit scale, well accepted by everyone in all the world, with the same meaning for all? It seems that the old dream by Ben Wright (to have a ruler and a scale easy to
interpret) must become true as soon as possible.
Regards
Agustin Tristan



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