| Exam Board | AQA |
|---|---|
| Module | S1 (Statistics 1) |
| Year | 2012 |
| Session | January |
| Marks | 3 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Bivariate data |
| Type | Identify errors in correlation analysis |
| Difficulty | Moderate -0.8 This question tests basic conceptual knowledge that the product moment correlation coefficient must lie between -1 and +1, requiring only recall and simple identification of an impossible value. No calculation or problem-solving is needed—students simply need to recognize that (b) is definitely incorrect while (a) and (c) are plausible, making this easier than average. |
| Spec | 2.05f Pearson correlation coefficient |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| Probably correct | B1 | CAO; accept minimum of PC or Pc or pC or pc |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| Definitely incorrect | B1 | CAO; accept minimum of DI or Di or dI or di |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| Probably incorrect | B1 | CAO; accept minimum of PI or Pi or pI or pi. Notes: Ignore reasoning in all parts, unless it includes 2 of the 4 statements in which case \(\Rightarrow\) B0. If answers not labelled, assume above order. Definitely wrong, etc \(\Rightarrow\) B0; Likely correct, etc \(\Rightarrow\) B0 |
# Question 2:
## Part (a)
| Answer/Working | Marks | Guidance |
|---|---|---|
| Probably correct | B1 | CAO; accept minimum of PC or Pc or pC or pc |
## Part (b)
| Answer/Working | Marks | Guidance |
|---|---|---|
| Definitely incorrect | B1 | CAO; accept minimum of DI or Di or dI or di |
## Part (c)
| Answer/Working | Marks | Guidance |
|---|---|---|
| Probably incorrect | B1 | CAO; accept minimum of PI or Pi or pI or pi. Notes: Ignore reasoning in all parts, unless it includes 2 of the 4 statements in which case $\Rightarrow$ B0. If answers not labelled, assume above order. Definitely wrong, etc $\Rightarrow$ B0; Likely correct, etc $\Rightarrow$ B0 |
---2 Dr Hanna has a special clinic for her older patients. She asked a medical student, Lenny, to select a random sample of 25 of her male patients, aged between 55 and 65 years, and, from their clinical records, to list their heights, weights and waist measurements.
Lenny was then asked to calculate three values of the product moment correlation coefficient based upon his collected data. His results were:
\begin{enumerate}[label=(\alph*)]
\item 0.365 between height and waist measurement;
\item 1.16 between height and weight;
\item - 0.583 between weight and waist measurement.
For each of Lenny's three calculated values, state whether the value is definitely correct, probably correct, probably incorrect or definitely incorrect.
\end{enumerate}
\hfill \mbox{\textit{AQA S1 2012 Q2 [3]}}