Technique Masterclasses

Statistics 1

Frequency and Boundaries

WST01 (Statistics 1) — Topic Frequency and Grade Boundaries

Provenance: written 2026-09-28, built entirely on research/veridian/WST01-verified-facts.md (compiled 2026-09-12, spot-check addendum 2026-09-25) and cross-checked against forge-exam-technique-guide.md and codex-formula-and-method-bank.md in this same folder. No new PDFs, web fetches, or external searches were performed for this document — as those two documents' own provenance notes record, no local WST01 PDF archive exists anywhere on this machine, and the facts bank's own §3 is the only source used here. This is deliberately the narrowest of the three WST01 technique-hub documents: a frequency table and a grade-boundaries check, nothing else.

How to use this document

Two things, and only two things, live here: which spec topics the verified past-paper record actually shows being tested, and whether real grade-boundary data exists for this paper. It is not a technique guide (that's FORGE) and not a formula reference (that's CODEX). Use the table below to weight your revision time by what has actually appeared, not by gut feeling about which topics "feel" examinable — and read the methodology note first, because the honest denominator here is smaller than "all 14 series," for reasons explained below.

1. Topic frequency and mark-weight

Methodology, stated plainly. The facts bank verified 14 series' question papers and mark schemes (Jun 2019 → Jan 2025), confirming the fixed 75-mark, 90-minute structure across all of them. But it only has genuine, systematic per-topic visibility — i.e. someone actually read what each question tested and what went wrong — for the 6 series whose examiner reports were located and fully read: Jun 2019, Jan 2021, Oct 2021, Jun 2022, Jan 2023, Jun 2024. The other 8 series (Jun 2021, Jan 2022, Oct 2022, Jun 2023, Oct 2023, Jan 2024, Oct 2024, Jan 2025) have their mark schemes verified for formula/notation conventions, but were not searched question-by-question for topic coverage — a few of them turn up in the facts bank anyway because a specific mark-scheme line was quoted for another reason (Oct 2022, Jan 2024, Jan 2025 each contribute one such citation below).

So: "N of 6" below means "confirmed tested, with a specific question/mark-scheme citation, in N of the 6 series with a fully-read examiner report." It is a verified lower bound on how often each topic appears, not a claim about the other 8 series — a topic absent from this table's count for a given series was very likely still tested that series (this is a fixed six-section spec sat every sitting); it just wasn't independently confirmed here. Do not read "0 of 6" for spec 1.1 as "never examined" — see its row for what was actually established.

Spec topicSeen in (of 6 ER series checked)Which seriesMark-weight evidence
1.1 Mathematical models (assumptions, refinement)0 of 6 as a standalone question—No dedicated marks found anywhere in the 14-series archive; the facts bank confirms this is a confirmed absence of a standalone question, not an unchecked gap. Content is examined embedded inside other questions (e.g. "assume the die is fair"), funded by AO3's unusually high 15–20/75 allocation across the whole paper.
2.1–2.4 Representation & summary of data (histograms, stem-and-leaf, mean/SD, coding, quartiles/IQR, outliers, box plots, comparing distributions)6 of 6Jun 2019, Jan 2021, Oct 2021, Jun 2022, Jan 2023, Jun 2024The only topic confirmed in every series checked. In the one series with a full verified per-question mark breakdown (Jan 2023), this content carried 10 of 75 marks (Q1).
3.1–3.4 Probability (conditional probability, independence, tree diagrams, Venn diagrams)4 of 6Jan 2021, Oct 2021, Jun 2022, Jan 2023Also independently confirmed present, via mark-scheme citation only (no ER), in Oct 2022. In Jan 2023's full breakdown, this content carried 10 of 75 marks (Q2). Pearson's own Jun 2022 general comment calls conditional-probability-vs-independence confusion a paper-wide weak point that series specifically.
4.1–4.3 Correlation and regression4 of 6Oct 2021, Jun 2022, Jan 2023, Jun 2024Also independently confirmed present, via mark-scheme citation only, in Jan 2024. In Jan 2023's full breakdown, this content carried 14 of 75 marks (Q6). Not confirmed for Jan 2021 or Jun 2019 in this research pass.
5.1–5.4 Discrete random variables5 of 6Jan 2021, Oct 2021, Jun 2022, Jun 2019, Jun 2024Also independently confirmed present, via a full mark-scheme worked example, in Jan 2025 (Q1, spanning nearly the whole sub-topic in one question). In Jan 2023's full breakdown this content carried the largest combined share seen on any one series — 24 of 75 marks across two separate questions (Q3+Q4) — but that two-question split is a feature of that one series' 8-part structure, not a claim about a typical share. Not confirmed for Jan 2023 itself in the ER (its two discrete-RV questions were identified by inference from a separate facts-bank citation, not by a direct examiner-report quote — see FORGE guide §1).
6.1 The Normal distribution5 of 6Jan 2021, Oct 2021, Jun 2022, Jan 2023, Jun 2024The richest single sub-topic in the facts bank — every one of these 5 examiner reports devotes at least one full question to it. In Jan 2023's full breakdown it was the single largest question on the paper: 17 of 75 marks (Q5), close to a quarter of the whole exam. Not independently confirmed for Jun 2019 in this pass (absence of citation, not confirmed absence).

Reading this table correctly. Two real, defensible conclusions: (1) Section 2 (data representation/summary) is the only topic confirmed on literally every series checked — it is a safe assumption every real paper includes it; (2) the Normal distribution (6.1) is confirmed as the paper's single heaviest-weighted question wherever a full mark breakdown exists, and every examiner report that discusses it independently calls it the most discriminating content on the paper. Beyond those two points, treat the "N of 6" counts as evidence of frequency of confirmed appearance in this research pass, not as a claim that a topic missing a citation for a given series wasn't tested there.

2. Grade boundaries

No real grade-boundary data exists anywhere in the source material used for this document. WST01-verified-facts.md was checked directly for "grade boundary," "boundaries," and "raw mark" (the terms Pearson uses in its published grade-boundary documents) and returns zero matches — the facts bank never fetched or verified a Pearson grade-boundary table for WST01 at any point in its research pass, and neither the FORGE guide nor the CODEX bank in this same folder mentions one either.

This document does not invent one. If grade-boundary figures are needed, they would have to be pulled fresh from Pearson's own published grade-boundary documents (qualifications.pearson.com, typically one PDF per series, per qualification) — that is new research this task's brief explicitly did not authorise ("no local PDF archive exists for this paper... don't attempt new fetches"), so it is flagged here as a genuine, open gap rather than filled with a plausible-looking number.

Sources and limitations