search for: 4pl

...'am! This is Alyssa Fatmah S. Mastura taking up Master of Science in Statistics at Mindanao State University-Iligan Institute Technology (MSU-IIT), Philippines. I am currently working on my master's thesis titled "Comparing the Three Estimation Methods for the Four Parametric Logistic (4PL) Item Response Model". While I am looking for a package about Markov chain Monte Carlo (MCMC) method for 4PL model in this R forum, I found an sirt package of an MCMC method but only for the three parametric normal ogive (3PNO) item response model. However, my study focus on 4PL model. In line...

...fy the likelihood for the upper asymptote yourself. -----Original Message----- From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of ALYSSA FATMAH MASTURA Sent: Thursday, January 18, 2018 10:15 AM To: r-help at r-project.org Subject: [R] MCMC Estimation for Four Parametric Logistic (4PL) Item Response Model Good day Sir/Ma'am! This is Alyssa Fatmah S. Mastura taking up Master of Science in Statistics at Mindanao State University-Iligan Institute Technology (MSU-IIT), Philippines. I am currently working on my master's thesis titled "Comparing the Three Estimation Meth...

WinXP, Splus7 and R2.3.1. All, I have been using the SSfpl and SSlogis self-starting functions in the nlme library to fit 4PL and restricted 4PL models. I need to adapt these routines to fit the alternative model f(x) = A + (B-A)/(1 + abs(x/EC50)^C) My Question: How do I obtain good starting values for this alternative model? (The pseudo-code found on pages 517 - 520 of "Mixed Effects Models in S and Splus&qu...

...uld you please help me with this? Cheers Pete PLEASE CONSIDER THE ENVIRONMENT BEFORE PRINTING THIS E-MAIL For Aon’s standard conditions associated with this e-mail please visit http://www.aon.com/uk/en/email-footer/aon-limited.jsp Aon Limited Registered Office: 8 Devonshire Square, London EC2M 4PL Registered in London No. 210725 . VAT Registration No. 480 8401 48 Aon Limited is authorised and regulated by the Financial Services Authority in respect of insurance mediation activities only. [[alternative HTML version deleted]]

All, I have been learning about mixed models and have been able to successfully use lme( ) and nlme( ) to fit some simple linear and 4PL logistic models. As a relative "newbie" I am at a loss as to how I can do the following: (1) Import a SAS dataset with DATE9. formatted time values and get them converted into a convenient time variable for use with the nlme package. In particular, I would like to use the...

Hi, I am currently trying to do dose-response curves using weighted 4-parameter model (4PL). The weighting was based on 1/(expected variance) derived from historical data. I tried both drm() from drc package, and nls(), found very different results derived from drm() vs. nls() using "weights=" argument. d1<-read.table("d1.txt",sep='\t',header=T,row.names=...

Hi, I am not sure this is a bug but I can repeat it, The functions and data are below. I know this is nasty data, and it is very questionable whether a 4pl model is appropriate, but it is data fed to an automated tool and I would have hoped for an error. Does this repeat for anyone else? My details: > version _ platform i686-pc-linux-gnu arch i686 os...

...----------------------- PLEASE CONSIDER THE ENVIRONMENT BEFORE PRINTING THIS E-MAIL For Aon’s standard conditions associated with this e-mail please visit http://www.aon.com/uk/en/email-footer/aon-limited.jsp Aon Limited Registered Office: 8 Devonshire Square, London EC2M 4PL Registered in London No. 210725 . VAT Registration No. 480 8401 48 Aon Limited is authorised and regulated by the Financial Services Authority in respect of insurance mediation activities only. [[alternative HTML version deleted]]

Hello, I am trying to fit my Elisa results (absorbance readings) to a standard curve. To create the standard curve model, I performed a 4-parameter logistic fit using the 'drc' package (ExpectedConc~Absorbance). This gave me the following: > FourP A 'drc' model. Call: drm(formula = Response ~ Expected, data = SC, fct = LL.4()) Coefficients: b:(Intercept) c:(Intercept)

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello, I've set up a namespace to share some mailboxes. When I try to select them, I get an internal error: Client-server chat: * OK Dovecot ready. 1 login dvtest2 x 1 OK Logged in. 2 list "" * * LIST (\HasNoChildren) "." "Trash" * LIST (\HasChildren) "." "test" * LIST (\HasNoChildren)