Audit the model chooser and the sample size page

src/pages/ModelChooser.test.tsx

@@ -72,10 +72,10 @@ const PATHS: { clicks: RegExp[]; id: string; model: string; code: string; lesson
   { clicks: [/middle step, or/i, /^an effect through a middle step$/i], id: 'mediation', model: 'Mediation model', code: 'indirect := a * b', lessonId: '17-1' },
   { clicks: [/middle step, or/i, /hang together/i], id: 'scale-reliability', model: "Scale reliability (Cronbach's alpha)", code: 'psych::alpha(items)', lessonId: '03-4' },
   { clicks: [/summing up/i, /traits behind them/i], id: 'exploratory-factors', model: 'Exploratory factor analysis (EFA)', code: 'factanal(', lessonId: '17-2' },
-  { clicks: [...YES_NO, /a cross-table/i], id: 'cross-table', model: 'Chi-square test of independence', code: 'chisq.test(', lessonId: '09-3' },
-  { clicks: [...YES_NO, /one percentage/i], id: 'proportion-vs-value', model: 'Exact binomial test', code: 'binom.test(', lessonId: '09-1' },
-  { clicks: [TO_OUTCOME, /no order/i, /linked to one other category/i], id: 'cross-table', model: 'Chi-square test of independence', code: 'chisq.test(', lessonId: '09-3' },
-  { clicks: [TO_OUTCOME, /ordered levels/i, /groups differ, or/i], id: 'rank-tests', model: 'Rank-based tests', code: 'kruskal.test(wellbeing ~ department, data = d)', lessonId: '12-4' },
+  { clicks: [...YES_NO, /a cross-table/i], id: 'cross-table', model: 'Traditional chi-square test of independence', code: 'chisq.test(', lessonId: '09-3' },
+  { clicks: [...YES_NO, /one percentage/i], id: 'proportion-vs-value', model: 'Traditional exact binomial test', code: 'binom.test(', lessonId: '09-1' },
+  { clicks: [TO_OUTCOME, /no order/i, /linked to one other category/i], id: 'cross-table', model: 'Traditional chi-square test of independence', code: 'chisq.test(', lessonId: '09-3' },
+  { clicks: [TO_OUTCOME, /ordered levels/i, /groups differ, or/i], id: 'rank-tests', model: 'Traditional rank-based tests', code: 'kruskal.test(wellbeing ~ department, data = d)', lessonId: '12-4' },
   { clicks: [BAYES, /your own priors/i], id: 'bayesian-regression', model: 'Bayesian linear regression (brms)', code: 'brm(', lessonId: '16-4' },
 ];
 
@@ -153,11 +153,11 @@ describe('ModelChooser', () => {
   test('the traditional name is shown only when the leaf has one', async () => {
     renderChooser();
     await clickThrough([...GROUPS, /^two groups$/i]);
-    expect(screen.getByText('Traditional name:')).toBeTruthy();
+    expect(screen.getByText('Traditional counterpart:')).toBeTruthy();
 
     await userEvent.click(screen.getByRole('button', { name: /start over/i }));
     await clickThrough([...NUMERIC, /several predictors/i]);
-    expect(screen.queryByText('Traditional name:')).toBeNull();
+    expect(screen.queryByText('Traditional counterpart:')).toBeNull();
   });
 
   test('every node in the tree is well formed', () => {
@@ -294,7 +294,7 @@ describe('links and the index', () => {
     await userEvent.type(search, 'kruskal');
     expect([...index.querySelectorAll('.model-card button')].map((button) => button.textContent)).toEqual([
       'Linear model with a categorical predictor',
-      'Rank-based tests',
+      'Traditional rank-based tests',
     ]);
 
     await userEvent.clear(search);

src/pages/ModelChooser.tsx

@@ -95,7 +95,7 @@ function AnswerCard({ answer }: { answer: Answer }) {
       </p>
       {answer.traditional && (
         <p>
-          <strong>Traditional name:</strong> {answer.traditional}
+          <strong>Traditional counterpart:</strong> {answer.traditional}
         </p>
       )}
       <p>
@@ -159,7 +159,7 @@ function Index({ onPick }: { onPick: (id: string) => void }) {
     <section className="model-index" aria-labelledby="model-index-title">
       <div className="model-index-head">
         <h2 id="model-index-title">Browse all {entries.length} models</h2>
-        <p>Already know what you need? Search by name, or by the test you know it as.</p>
+        <p>Already know what you need? Search by name, or by the traditional test you know it as.</p>
       </div>
       <div className="model-index-tools">
         <label className="model-index-search">
@@ -168,7 +168,7 @@ function Index({ onPick }: { onPick: (id: string) => void }) {
             <circle cx="8.5" cy="8.5" r="5.5" fill="none" stroke="currentColor" strokeWidth="2" />
             <path d="M13 13l4.5 4.5" stroke="currentColor" strokeWidth="2" strokeLinecap="round" />
           </svg>
-          <input type="search" value={query} onChange={(event) => setQuery(event.target.value)} placeholder="Search, for example t-test or mediation" />
+          <input type="search" value={query} onChange={(event) => setQuery(event.target.value)} placeholder="Search, for example mediation or a traditional test" />
         </label>
         <div className="model-index-filters" role="group" aria-label="Show">
           {FILTERS.map((option) => (
@@ -498,8 +498,8 @@ export default function ModelChooser() {
 
         <p className="model-chooser-legend">
           Most snippets run as they are in the <Link to="/workspace">R Workspace</Link>, and the ones that need RStudio say so.
-          Each reads workplace.csv or wellbeing-population.csv, the course data the workspace already has, or a dataset built
-          into R when the course data has nothing that fits. For your own data, change the file name in read.csv() and the
+          Each reads workplace.csv or wellbeing-population.csv, the course data the workspace already has, or a dataset that
+          comes with R or with the package the snippet uses, when the course data has nothing that fits. For your own data, change the file name in read.csv() and the
           column names.
         </p>
       </section>

src/pages/SampleSize.test.tsx

@@ -54,11 +54,11 @@ describe('sample size page', () => {
     expect(question()).toBe('The sample you need');
     // pwr.t.test(d = 0.3, power = 0.8) gives n = 175.4 per group.
     expect(report()).toContain('352 participants (176 per group)');
-    expect(report()).toContain('d = 0.30 with 80% power in a two-sided independent-samples t-test at α = .05');
+    expect(report()).toContain('d = 0.30 with 80% power in a two-sided test of the group difference (the traditional independent-samples t-test) at α = .05');
     // 176 / 0.9 rounds up to 196 per group.
     expect(report()).toContain('we will recruit 392 participants');
     expect(screen.getByText(/pwr.t.test\(d = 0.3, sig.level = 0.05, power = 0.8/)).toBeTruthy();
-    expect(screen.getByText(/is the independent-samples t-test \(Lesson 12-1\)/)).toBeTruthy();
+    expect(screen.getByText(/is the same as the traditional independent-samples t-test \(Lesson 12-1\)/)).toBeTruthy();
     expect(trail()).toEqual(['Compare two separate groups', 'Plan a new study', 'My own guess of the scores', 'd = 0.30', '80% power', 'α = .05', 'Two-sided', '10% dropout']);
   });
 
@@ -214,8 +214,8 @@ describe('sample size page', () => {
     expect(question()).toBe('How many people will you lose?');
     await pick(/^None/);
     // λ = N·f² with df2 = N − 2: 128 people, 64 per group.
-    expect(report()).toContain('128 participants (64 per group, each measured in both conditions) are needed to detect an effect of f = 0.25 (with a correlation of r = .50 between conditions)');
-    expect(report()).toContain('the F test for the interaction in a 2 × 2 mixed ANOVA');
+    expect(report()).toContain("128 participants (64 per group, each measured in both conditions) are needed to detect an effect of f = 0.25 (an f that already includes the correlation of r = .50 between conditions; in G*Power's repeated-measures procedures, with r = .50, this is f = 0.125)");
+    expect(report()).toContain('the F test for the interaction in a 2 × 2 mixed design, one factor between and one within people (a traditional mixed ANOVA)');
     expect(trail()).toContain('One factor between, one within');
   });
 
@@ -227,7 +227,7 @@ describe('sample size page', () => {
     await pick(/Whether one factor's effect depends on the other/);
     expect(question()).toBe('How big is the effect you want to be able to find?');
     await pick(/Choose a size in plain words/);
-    const disappears = screen.getByRole('button', { name: /The effect disappears \(f = 0.13\)/ });
+    const disappears = screen.getByRole('button', { name: /The effect disappears \(f = 0.125\)/ });
     expect(disappears.textContent).toContain('Recommended');
     // f = 0.5 / 4 = 0.125: λ = N/64 reaches 80% power at 508 people (127 per cell), as in R.
     expect(disappears.textContent).toContain('Needs about 508 people');
@@ -236,6 +236,7 @@ describe('sample size page', () => {
     await pick(/α = \.05/);
     await pick(/^None/);
     expect(report()).toContain('508 participants (127 in each of the four cells)');
+    expect(report()).toContain('an effect of f = 0.125');
   });
 
   test("the browser's Back button goes back one question, keeping the answers", async () => {