Merge pull request #71 from zhanglj37/main

update difficulty simulatin webpage

Author: ben-domingue

diffsim.qmd

@@ -41,25 +41,15 @@ The current difficulty pool includes 145 datasets from IRW (as of 10-2025), cove
 </div>
 
 
-
-
- 
-Below is the figure showing how varied these distributions can be — some centered, some skewed, some even multimodal. This diversity helps us better understand how measurement behaves under realistic conditions.
-
-
-```{r, message = F}
+```{r, eval=FALSE}
 # load the difficulty pool from the package
-devtools::install_github("itemresponsewarehouse/Rpkg") 
 data("diff_long", package = "irw")
 
 # package for plot
 library(dplyr)
 library(ggplot2)
 library(ggridges)
-```
-
 
-```{r, fig.width=4, fig.height=7, fig.align='center'}
 diff_long_sd <- diff_long |>
   group_by(dataset) %>%
   mutate(SD = sd(difficulty, na.rm = TRUE)) %>%
@@ -79,11 +69,15 @@ ggplot(diff_long_sd, aes(x = difficulty, y = reorder(dataset, SD), fill = SD)) +
   )
 ```
 
-<!--div style="text-align: center;">
+ 
+Below is the figure showing how varied these distributions can be — some centered, some skewed, some even multimodal. This diversity helps us better understand how measurement behaves under realistic conditions.
+
+
+<div style="text-align: center;">
   <img src="diffsim/ridge_irw.png" alt="Distribution of Item Difficulties" width="40%">
 
 <p style="font-size: 0.9em; color: gray;"><strong>Note:</strong> The color intensity reflects the standard deviation of difficulties in each dataset, with darker shades signifying greater variability.</p>
-</div-->
+</div>
 
 
 
@@ -108,7 +102,7 @@ The sample size requirement analysis demonstrates the strong influence of item d
 
 
 <div style="text-align: center;">
-  <img src="/diffsim/scatter_sd_logminn.png" alt="Distribution of Item Difficulties" width="60%">
+  <img src="/diffsim/scatter_sd_logminn.png" width="60%">
 </div>
 
 ## Reference