Local food networks and the change of the agrofood system

Can alternative local food networks, through the relocalization of production and consumption and the higher proportion of organic practices, bring significant changes in the agrofood system? Drawing on the case of French Amaps, the distinction between an “input substitution paradigm” and a “system redesign” paradigm, which is at the crossroads of agricultural and social sciences, will help to assess the changes which occur in consumers and producers practices and in their interactions

Interpreting gains and losses in conceptual test using Item Response Theory

Conceptual tests are widely used by physics instructors to assess students' conceptual understanding and compare teaching methods. It is common to look at students' changes in their answers between a pre-test and a post-test to quantify a transition in student's conceptions. This is often done by looking at the proportion of incorrect answers in the pre-test that changes to correct answers in the post-test -- the gain -- and the proportion of correct answers that changes to incorrect answers -- the loss. By comparing theoretical predictions to experimental data on the Force Concept Inventory, we shown that Item Response Theory (IRT) is able to fairly well predict the observed gains and losses. We then use IRT to quantify the student's changes in a test-retest situation when no learning occurs and show that $i)$ up to 25\% of total answers can change due to the non-deterministic nature of student's answer and that $ii)$ gains and losses can go from 0\% to 100\%. Still using IRT, we highlight the conditions that must satisfy a test in order to minimize gains and losses when no learning occurs. Finally, recommandations on the interpretation of such pre/post-test progression with respect to the initial level of students are proposed