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The validity of a measurement instrument

The essence of the validity of the IMES is centered in the degree of safety in which each question identifies a present positive or negative action in a subject. It is hoped that the tool will be very axe in identifying that something and not something else. The degree of safety in which the tool identifies that something, constitutes the degree of validity of the measurement instrument. The IMES in the test experience showed be valid in an average of 96,3% of the times to identify the potential of present negative actions in a subject such as: theft, discrimination, lie, envy, adultery, acts hartful and death.

To control if exists actually in the subject the positive or negative act that identifies the IMES and is committing a measurement mistake, it should be to use a second questionnaire called questionnaire of control(1), The questionnaire of control is applied immediately after applying the IMES, this questionnaire serves to investigate and confirm the trend of the subject to committing negative or positive acts.

Then through a correlation test statistics was proceeded to compare the qualifications of all the subjects in the two questionnaire, the questionnaire IMES and the questionnaire of control. The resulting value in the correlation can oscillate among zero (0,0) and zero point ninety and nine (0,99) with trend to one (1), among nearest to one (1) the value of the test, more valid will be the instrument to measure potentially positive or negative actions in the subject. The following is the chronology of the validation of the IMES:

No TestSample SizesValidity Level
0smaller sizes to 30 subjectsmaller that 0,5

The validity average of the IMES in the last three tests, those which surpass the confidence level agreed to sciences sociales(2) is of 96,3%.

In the third left column to straight (validity level), is observed that the correlation level of the different tests are behaved in rising address with trend to one (1). The foregoing indicates that the IMES in progressive form was going reducing the possibility of the fact that by mistake did not register the potential trend of the subject to having negative actions. That is to say the possibility of the fact that the individual in spite of have recognized in the questionnaire of control that had trend to negative actions and the IMES not registered it thus, was every time smaller until reaching a level of mistake probability by below of the 5%.

The under mistake level of the IMES (smaller of the 5%) in what concerns to the mistake in not to register negative potential actions in the subject, recommend this instrument as a valid tool to measure the trend of the individual to accomplish negative or positive actions, at the same time the IMES is valid to prove the capacity of an antidote to avoid in a subject the reproduction of the violence.

1 As questionnaire of control to ask to individual about the securities, was used the decalogue or the ten orders presented in The Bible Jerusalem. Bilbao: Editorial:Desclée of Brouwer, S.A, Exodus 20, to see 1- 17.

2 Roberto Hernández Sampieri & other, Methodology of the investigation. Mexico: Mc Graw hill, 1991, pg 377.

The reliability of a measurement instrument

The measurement instrument IMES was submitted to a reliability test, in order to that its results will be considered with certain degree of confidence. What is reliable of the instrument makes reference at conformity level that is waited, if the test is arrived to apply in two different dates from the same subject, letting go by a prudent time among a test and the other so that the subjects do not keep in the report the answers. The comparison of the two tests must register a conformity among the qualification of the second test in relationship to the qualification of the first test, provided that they may not have been incorporated in the subjects, during the time, a factor or antidote that vary the answers affecting the conformity.

The IMES was submitted to the type of reliability test called "Stability Measure" (reliability by test - retest)3, This test consists in applying for the first time the questionnaire to a group of subjects, after is let go by a time and is repeated for the second time the test to the same group. It is hoped that the result of the second measure not change in relationship to the first test, unless also there is assorted the situation in the subjects.

It was proceeded to accomplish the reliability test; the questionnaires applied to each subject in the two tests were qualified in a scale of (0) to (10) points, were found the following results: The maximum difference in the qualification of the two tests was of 3,0 points and the minimal difference of 0,0 points. The standard deviation of the difference was of 1,0 point. The average of difference among a test and other was of 1,0 point.

The previous data indicate that the IMES has the trend to present stable results, the trend in the test is to maintain similar results, without much variation. It is recommended the IMES as a reliable instrument, that is to say if is measured today to some subjects, is let go by a time and again are measured the same individual, the IMES has the trend to show the same results, unless may have happened something particular that affect the life of the subjects and consequently to the measurement.

3 Roberto Hernández Sampieri & other, Methodology of the investigation. Mexico: Mc Graw hill, 1991, pg 249.