Appendix C — StatLens Quick Reference
StatLens is a free, browser-based statistics toolkit used throughout this textbook. Every chapter has links to the specific tools it needs.
Browse all tools. The full up-to-date tool index lives at learnlens.org/statlens — distribution calculators, simulation tools, guided activities, and conceptual demos. That is the authoritative catalog. This appendix collects only the two things you may want offline: keyboard shortcuts and the URL parameters used to build reproducible links.
C.1 Keyboard shortcuts
Every StatLens page supports the same keyboard shortcuts. Handy in a lecture demo where you want to advance a simulation without your hand leaving the keyboard.
| Key | Action |
|---|---|
1 |
Generate +1 sample or resample |
2 |
Generate +10 |
3 |
Generate +100 |
4 |
Generate +1000 |
0 |
Reset the simulation |
Space |
Play / pause an animation |
? |
Show the keyboard help overlay |
Esc |
Close a dialog or overlay |
C.2 URL parameters
StatLens URLs accept query-string parameters so a link can pre-load a dataset, seed the RNG, or set the confidence level. Instructors use this to build reproducible in-class demos and homework links whose answers are gradeable against a known seed.
The seed parameter uses the same PRNG (sfc32) as StatLens’s internal generator, so two viewers loading the same seeded link see the exact same sequence of draws. This is what makes seeded homework problems in MyOpenMath auto-gradeable: the assignment engine picks a seed, pre-computes the expected result, then grades the student’s answer against it.
Common parameters (not every tool accepts every parameter; each tool’s page documents which ones apply):
| Parameter | Example | Meaning |
|---|---|---|
seed |
?seed=42 |
Deterministic PRNG seed |
dataset |
?dataset=diamonds |
Load a named built-in dataset |
data |
?data=1,2,3,4,5 |
Load inline comma-separated data |
n |
?n=30 |
Set sample size |
p |
?p=0.5 |
Set a probability parameter |
mu |
?mu=100 |
Set a mean |
sigma |
?sigma=15 |
Set a standard deviation |
ci |
?ci=95 |
Set confidence level (percent) |
alt |
?alt=greater |
Alternative-hypothesis direction (less, greater, two-sided) |
plot |
?plot=only |
Show only the plot (hide controls) — useful for embedding |
cutlines |
?cutlines=ci or ?cutlines=tail |
Draggable cut-lines: CI bounds or tail-area |
Combine parameters with &:
https://learnlens.org/statlens/simulate/bootstrap-mean/?dataset=diamonds&seed=42&ci=95For the authoritative parameter list per tool, see the docs at learnlens.org/statlens/docs/url-api.md.