[Rasch] 回复: Questions about interpreting wright/item map for rating scale model

Yingchen 2596011329 at qq.com
Wed Jul 22 11:03:23 AEST 2020

Thank you, Rebecaa.
Really appreciate your help.
I once tried to align the values in item parateter files with the graph, uing the bparameter and se, but I couldn't. What I didn't do were (1) use another pogram, and (2) use 3*SE, which will yield 99% CI. 
I will use the program you mentioned in the email.
Really appreciate your help.

------------------ 原始邮件 ------------------
发件人:                                                                                                                        "Rebecca L Freund"                                                                                    <rlfreund at berkeley.edu>;
发送时间: 2020年7月21日(星期二) 晚上9:30
收件人: "Yingchen "<2596011329 at qq.com>;"rasch"<rasch at acer.edu.au>;
抄送: "david"<david at torresirribarra.com>;
主题: Re: [Rasch] Questions about interpreting wright/item map for rating scale model



The lines are connecting different parameters from the same item. The dots indicate the parameter locations. It looks like your first item has step parameters around 1 and 4, your second item’s parameters are around -4 and -1, etc. The line and shapes are simply to help distinguish the items. The last two items have extra dots because those items have more score categories than the first 17 items.

David Torres Irribarra and I have written a package for R to create this type of map, with a lot of customization options. It is available on CRAN as WrightMap, or you can download the most recent development build at https://github.com/david-ti/wrightmap. More information is available at our website, WrightMap.org, or feel free to reach out if you have any questions.



On July 21, 2020 at 4:33:52 AM, Yingchen (2596011329 at qq.com) wrote:
 Dear Rasch lovers:
     Can someone tell me how to interprete the wright/item map for the rating scale model? I attached the graph  from jMetrik. 
     I read user's manual for jMetrik, some publications and tutorials on item map and checked the estimated item values. I could understand the map with histogram on the left and dots on the right, but not this graph. I checked and thought the graph was produced correctly. 
    Would appreciate if anyone can help with the following questions.
   Q1: What do the lines mean? They must represent the item parameter estimates. However, I cannot align them with the item file. 
   Q2: What do the different shapes on the lines represent? There are squares, diamonds,circles, rectangles, arrows, arrows pointing to different directions. My guess is that the software developers used different shapes to enable readers to tell the different items. 
   Q3: What do the square and the circle in the middle of the last two lines represent?  I know that they should have something to do with the item parameter estimates. 
   Q4: is the length of each line related to confidence interval of item parameter estimate? 
   Q5. Can anyone recommend non-commerical softwares with the capacity to produce the the item map? 

   BTW, I did send a message to jMetrik help 2 days ago, but there was no reply.
   Any help is greatly appreciated. 
   Thank you for your time and attention. 

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