Stack Overflow
Stack Overflow

Questions tagged [bradleyterry2]

11 questions
2
votes
1 answer

BradleyTerry2 package in R - Using null hypothesis as reference player

I am using the BradleyTerry2 package in R to analyse my data. When using the BTm function to calculate ability scores, the first item in the dataset is removed as a reference, given a score of 0 and then other ability scores are calculated relative…
Invisi
  • 23
  • 4
2
votes
1 answer

Calculate BradleyTerry Ability rankings

I'm trying to output the estimates of ability from a Bradley Terry model using the BradleyTerry2 package in R. I keep getting a very cryptic error. Some of the examples from their documentation work and others return the same error I get using my…
Will Cornwell
  • 241
  • 2
  • 9
1
vote
0 answers

Bradley Terry model for pairwise preference data in r

Background For my thesis, I have conducted a pairwise cafeteria experiment in which pairs of fruit are presented to birds and it is recorded which they chose. From the research, I have found that the appropriate model to analyse this data is a…
Lwes
  • 11
  • 1
1
vote
1 answer

Issue with Predictor Variables in BradleyTerry2 package

I'm trying to include contest-specific variables in my data analysis using the BradleyTerry2 package in R.3.3.1 (I also tried with R.2.11.1 to compare with an older version of BradleyTerry2). The problem I face is that my predictor variables are not…
C. Rigal
  • 11
  • 3
1
vote
1 answer

R model fitting routine fails to run in a function

I'm using Firth and Turner's BradleyTerry2 package for paired comparisons but have run into a mysterious problem using the main fitting function BTm. Here is a minimal data setup from their own example: data(citations, package =…
conjugateprior
  • 398
  • 1
  • 15
1
vote
1 answer

Updated with data: Error in Diff...must be factors with the same levels

I hope you all can help me. I have a list with two data frames -- contests and expvar. In the data frame contests, each row is a match with the first column being the winner of the match, and the second column being the loser of the match. In…
Eva
  • 23
  • 4
0
votes
0 answers

What is the relationship between the BradleyTerry model and the Generalized Davidson model in the BradleyTerry2 package in R?

I've been familiar to the BraleyTerry model proposed in 1952 .And In 1970 Davidson promoted a generalized model with ties. `your text` '$$ P(\text{ties}) =\frac{\nu\sqrt{\alpha_i\alpha_j}{\alpha_i+\alpha_j+\nu\sqrt{\alpha_i+\alpha_j}} $$ $$ …
love y
  • 1
0
votes
2 answers

using sapply with a function that has multiple arguments

I have a list of multiple data frames (called prep1). Each data frame has the following format(only the first 6 rows shown) player1 player2 win1 win2 1 a12TTT.pdf a21.pdf 0 1 2 a12TTT.pdf B11.pdf 1 0 3 a12TTT.pdf …
Vasile
  • 1,017
  • 2
  • 10
  • 19
0
votes
1 answer

BradleyTerry2 package missing one player in model results

I have data on 23 'players'. Some of them played against each other (but not every possible pair) one or multiple times. The dataset I have (see dput below) includes the number of times one player won and lost against another player. I use it to…
Vasile
  • 1,017
  • 2
  • 10
  • 19
0
votes
1 answer

R setting one item as reference variable

This might be very obvious but I am not seeing it. Normally, if one wants to set one variable out of an array as 'reference', the easiest thing to do is subtract. e.g [1,4,10,9,6] set item 2 at reference, [-3,0,6,5,2]. How can the original be…
ha554an
  • 103
  • 6
0
votes
1 answer

R library(BradleyTerry2). Error in Diff(player1, player2... must be factors with the same levels

I have a problem using BradleyTerry2 package in R. My data looks like as below. I created the data from another code, and I think the format is same to the "citations.sf" in BradleyTerry exmple…
pico123
  • 3
  • 1