4.d) Social and technical issues
4.d.1. Shortage of statistical studies with adequate IQ data
The studies of intelligence quotients in families with a large sample are scarce because the fieldwork that includes these type of variables tend to be more directed at studies of identical twins, twin brothers or adoption programs, and do not include the two progenitors.
If there were one study, it would be nice to have access to its row data.
The results are also quite costly to have a guarantee of objectivity. For instance, the study needs a good sample design; there is the additional difficulty of obtaining volunteers for this type of statistical study, and the performance of the intelligence test by specialized personnel.
4.d.2. Access to the quantitative data source
Nevertheless, the most complicated thing was to find and access the original quantitative data source to perform the statistical research and estimations within the EDI Study.
Despite the small magnitude of the analyzed sample, the generation of variables by different groupings and criteria of the available values has allowed for the accessibility of a sensitive model to the information. This characteristic is one of the model's strong points; even with the vulnerability of the researched correlations, it is significant that some determination coefficients are close to the unit and that the thousands of checks carried out have a high level of consistency.
In defense of the small sample of quantitative data, we would like to say that, asking for statistical data on intelligence quotients (IQ) of families, we have been virtually traveling for more than one year to numerous worlds of professionals, national and international organizations dedicated to the study of intelligence, public organisms, universities, Internet newsgroups, and international studies on twins. We even turned over the search to a psychometric company, but there were no results.
In the end, a search performed by the Google server's paid service found four different sites. We had entered three of them before and did not found the information. Fortunately, the fourth gave its fruits, although with some difficulty. At least we obtained a sample of quantitative data, even though it was small.
It must be that the personal character social and political implications hinder the access to the statistical data.
Likewise, we imagine that the authors of the majority of the thousands of statistical research articles published on this subject probably did not have access to the quantitative data source and limited themselves to commenting on the results published by other works and theoretical justifications of their point of views.
4.d.3. Modern computer technology
Statistical research with sensitivity analysis of multiple correlation coefficients obtained by linear regression requires a great deal of knowledge of statistical techniques.
The analysis of the correlations of variables with computer models of regression by ordinary least squares is available for quite some time.
Nonetheless, the computer capacity of calculation has spectacularly multiplied in recent years. The use of this high capacity of modern computer technology has been essential to obtain the results achieved in the statistical research of the EDI Study.
It is worth pointing out that each time we reorganize the quantitative data, the Excel math worksheet generates more than 10,000 random numbers, hundreds of variables, more than 100,000 coefficients of determination of linear regression for ordinary least squares of the different variants of the model, and presents 200 graphs with 16,000 values, that are, of course, in color. It used to take 3 to 7 seconds.