In this paper, we investigate two purported problems with Bayesian Knowledge Tracing (BKT), a popular statistical model of student learning: "identifiability" and "semantic model degeneracy." In 2007, Beck and Chang stated that BKT is susceptible to an "identifiability problem"--various models with different…

Age-period-cohort (APC) models are designed to estimate the independent effects of age, time periods, and cohort membership. However, APC models suffer from an identification problem: There are no unique estimates of the independent effects that fit the data best because of the exact linear dependency among age, period, and cohort. Among methods…

In a pilot study of about 400 public high school students in Chicago, four innovative approaches are employed to deal with previous research problems arising from the study of juvenile delinquency: specific, proximal measures of social background, multiple indexes of delinquency, anonymous self-reports of delinquency incidence, and parametric…

Discusses the relationship between changes in delinquency prevalence over time and prediction error. Data from a 21-year British longitudinal study exemplify the formal relationships that are derived. Results indicate statistically, as prevalence increases, a relative increase in false negative errors and a decrease in false positive errors…

Addressing a common problem in the analysis of social networks, this study describes quantitative techniques for identifying social subgroups using individual perceptions of social affinities within natural groups. Compared are four analytic methods for abstracting composite representations of sub-structures. These methods, formally evaluated…

Reviews several potential problems that often invalidate statistical tests of social theories. Discusses how there may be very serious identification problems in the estimation of the relationship between executions and homicides, and that serious questions may be raised regarding the validity of any particular estimation of this relationship.…

This project was part of the Portland High Impact Program and had as its goal a 60 percent reduction in burglary losses over a three-year period to be attained by installing centrally-monitored, silent, anti-intrusion devices in eleven schools. Comparison with eleven control schools indicates that the alarm system has demonstrated effectiveness in…