Edexcel IAL Psychology 4.2.7 Inferential Statistics

Practise Edexcel Psychology questions calculating chi-squared, completing observed and expected tables, and interpreting significance in research data.

Exam points

calculate chi-squared by completing observed, expected and contribution values
interpret a chi-squared result against a critical value and significance level

[Maximum number: 4]

Yoko carried out an observation in a local park. She observed how males and females interacted with other people, to see if there was a difference. She observed how long males spoke to males (Condition A) and how long females spoke to females (Condition B). Yoko observed if they spoke for less than 5 minutes or for 5 minutes or more.
Yoko recorded her data using event sampling.

Yoko carried out a chi-squared test on her data.
Calculate chi-squared for the data gathered by Yoko by completing Table 2.
Your answers must be correct to two decimal places.
(4)

Table 2 Space for calculations

\begin{tabular}[t]{l}
AO2 (4 marks)

Credit one mark for correct completion of O-E column Credit one mark for accurate completion of (O-E) ${ }^{2}$ column two decimal places Credit one mark for accurate completion of (O-E) ${ }^{\mathbf{2}}$ /E column to two decimal places Credit one mark for correct chi-squared to two decimal places =
\begin{tabular}[t]{|l|l|l|l|l|l|l|}
\hline

Observed

Expected

O-E

(O-E) ${ }^{\mathbf{2}}$ $\boldsymbol{(} \mathbf{O} \boldsymbol{-} \mathbf{E} \boldsymbol{)}^{\mathbf{2}} \boldsymbol{/} \mathbf{E}$

Condition A males spoke to males

Under 5
minutes

3

5.5

-2.5

6.25

1.14

5 minutes
or over

7

4.5

2.5

6.25

1.39

Condition B females spoke to females

Under 5
minutes

8

5.5

2.5

6.25

1.14

5 minutes
or over

2

4.5

-2.5

6.25

1.39

Chi squared =

5.06

\end{tabular}

Look for other reasonable answers.
\end{tabular}

(4)

All question bank results loaded

4.2.7 - List B inferential statistics question 1