feat(n_reps): add mcq (#145)

Author: amyheather

pages/guide/output_analysis/n_reps.qmd

@@ -1580,6 +1580,55 @@ Not relevant - replicating an existing model described in a paper, so just used
 
 ## Test yourself
 
+<div class="h3-tight"></div>
+
+### Quiz
+
+```{r}
+#| echo: false
+library(webexercises) # nolint: library_call_linter
+```
+
+::: {.callout-note}
+
+## Why do we need multiple replications when analysing a DES model?
+
+```{r}
+#| output: asis
+#| echo: false
+cat(longmcq(c(
+  "Because replications are required to remove all randomness from the model.",
+  "Because each replication uses a different model structure.",
+  answer = paste0(
+    "Because each run is affected by randomness, and averaging over many ",
+    "replications produces a more stable and reliable estimate."
+  )
+)))
+```
+
+:::
+
+::: {.callout-note}
+
+## What is the core idea behind the confidence interval method for choosing the number of replications?
+
+```{r}
+#| output: asis
+#| echo: false
+cat(longmcq(c(
+  answer = paste0(
+    "Increase the number of replications until the confidence interval ",
+    "around the mean becomes sufficiently narrow and stable."
+  ),
+  "Run a fixed, large number of replications regardless of variability.",
+  "Keep adding replications until the mean exactly matches a target value."
+)))
+```
+
+:::
+
+### Activity
+
 Have a go for yourself!
 
 Try out both the manual and automated methods described above to work out how many replications you need for your own simulation model.