R Code# This post builds on my recent post that builds a simulation of a computer adaptive test (CAT) selecting items from an infinite item pool using fisher information as the criteria.http://www.econometricsbysimulation.com/2012/11/computer-adaptive-...
Original Code# In order for us to understand what a Computer Adaptive Test (CAT) is, let's first think about how the CAT works.# A CAT test starts by having some kind of initial assessment of student ability (test taker's ability).# This is typically a...
Original Code# It is often times difficult to solve for the expected value of a variable in closed form.# However, using computers it can be easy to approximate.# Imagine (for whatever reason) you would like to calculate the expected value of exp(x) wh...
Original Code# One of the basic tasks in item response theory is estimating the ability of a test taker from the responses to a series of items (questions).# Let's draw the same pool of items that we have used on several previous posts:# First let's im...
Original Code# Computer adaptive tests "adapt" to test taker ability by making assessments of the test taker's ability and providing questions that are meant to maximize the amount of information that can be inferred from the test.# We often start by a...
Original Code# Matching Item Information# Imagine that you are asked to create a test from an item pool that you have.# The item pool has 100 items and you have to create a test of 20 items in length.# Easy right?# The trick is that the test creators w...
Original Code# Interestingly, one of the founders of Item Response Theory (Fredrick Lord) developed his own concept of information. His approach was both unique and interesting but ended up leaving us with the same Fisher Information Matrix.# The...
# This simualtion demonstrates how to build a simple spatial multi-agent simulations using R.# There is a 20 x 20 grid in which the agents occupy. If they walk into one edge they stop moving in that direction.gridx = 20gridy = 20# Let's first spe...
# I have been thinking of late about roommates and conflicts. It seems to me that the more roommates you have, the more likely you are to have some kind of explosive conflict. There seems to be very discrete thresholds.# I believe this is b...
# Power analysis is a frequently used tool to calculate the minimum sample size neccessary in order to show that a hypothesized result exists given some specified rate of type I and type II error. A typical level of error for type I is alpha=5%. ...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
