2.9 - Inference

WORK IN PROGRESS

This page is a Work In Progress. Please let us know if mistakes are still present here.

What Is 2.9 Inference All About?

Mathematics 2.9

Achievement Standard 91264

Use statistical methods to make an inference

4 Credits

Internal

This assessment is about _

The following page covers each of these skills and how to write the assessment.

Assessment Format

This standard is assessed as a short (800 words max) report completed in class time.

This report is digital and uses NZ Grapher to analyse the data.

The teacher can provide guidance on the plan, selection of dataset, size of sample, and can check that the question the student is asking will allow them to explain different sources of variation.

The teacher can also identify the population for the data and help with wording of the investigative question/statement.

All other work must be completed by the student during the time in class.

Skills for 1.1 Statistical Enquiry

This standard requires students to:

Complete an investigation about a dataset using the Statistical Enquiry Process (PPDAC) in one of four styles:
- comparison (numerical comparison of two or more groups)
- relationship (between two numerical variables)
- time series
- experimental probabilities (involving events with at least two stages).
Gather their own data through surveys or experiments or use existing data
Explain different sources of variation in data collection
Present data in an appropriate way
Describe what the data shows

PPDAC

Your report and process for writing the report for 2.9 Statistical Inference has 5 stages:

Problem
Plan
Data
Analysis
Conclusion

Problem

The Problem Statement is when you identify a problem to investigate.

Plan

Data

Analysis

Conclusion

Background

Students can also add some detail after their Problem Statement to explain why they chose this question and any background information that might be useful to a reader.

Hypothesis

After their Problem Statement, students can also add a hypothesis, whether they think their problem statement will be true and why they think this.

Enough Data or Reliable Enough Data?

You also need to consider if you had enough data or reliable enough data to make the call.

The minimum amounts of data needed to make a call are:

Relationship — 30 pairs of data.
Comparison — 30 pieces of data from each category explored.
Time series — 5 complete cycles.
Experimental probability — 30 trials.

Other Improvements?

You also need to consider if the experiment had any flaws at any stage in the PPDAC cycle.

Reflecting on how to improve the experiment is the difference between an Achieved and a Merit/ Excellence.

Additional Resources for 2.9 Inference

Liz Sneddon's website is very useful.

Ensure you have a strong knowledge of the Statistics parts of Junior Mathematics.

Practice Assessments and Marking Schemes

The following are practice assessments along with their marking schemes.

Page updated

Google Sites

Report abuse