The HERI Faculty Survey gathers comprehensive information about the faculty experience, such as position, field, institutional details, and personal opinion and views, including a single question asking respondents to self-identify their political orientation as "far left", "liberal", "moderate/middle of the road", "conservative", or "far right". Between 1989 and 1998, the survey showed negligible change in the number of professors who described themselves as far left or liberal, approximately 45%. , surveying 16,112 professors, the percentage of liberal/far left had increased to 60%. When asked in 2012 about the significance of the findings on political views, the director of HERI, Sylvia Hurtado, said that the numbers on political views attract a lot of attention, but that this attention may be misplaced because there may be trivial reasons for the shifts. Ladd and Lipset, who had conducted the original Carnegie survey, designed a telephone survey in 1999 of approximately 4000 faculty, administrators, and students, called the North American Academic Survey Study (NASS). Stanley Rothman, the project lead after the passing of Ladd and Lipset, published a paper using NAASS data along with Neil Nevitte and S. Robert Lichter which concluded "complaints of ideologically-based discrimination in academic advancement deserve serious consideration and further study". Rothman along with co-authors Matthew Woessner and April Kelly-Woessner reported their extended findings in a book titled "The Still Divided Academy". Neil Gross and Solon Simmons conducted a survey starting in 2006 called the "Politics of the American Professoriate" which led to several study papers and books. They designed their survey to improve on past studies which they felt had not included community college professors, addressed low response rates, or used standardized questions. The survey drew upon a sample size of 1417 full-time professors from 927 institutions. In 2007, Gross and Simmons concluded in "The Social and Political Views of American Professors" that the professors were 44% liberal, 46% moderates, and 9% conservative. "Inside Higher Ed" reported that economist Lawrence H. Summers made his own analysis of the data collected by Gross and Simmons and found a larger gap among faculty teaching "core disciplines for undergraduate education" at selective research universities, but the report also concluded that "there was widespread praise for the way the survey was conducted, with Summers and others predicting that their data may become the definitive source for understanding professors' political views." Gross published a more extensive analysis in his 2013 book "Why Are Professors Liberal and Why Do Conservatives Care?"