3.1 Statistics I

• Collection of data
• Frequency distribution tables for grouped and ungrouped data
• Mean, mode and median of grouped and ungrouped data
• Representation of data: histograms and frequency polygons
• Interpretation of data

• collect data from real-life sources
• draw a frequency distribution table for grouped and ungrouped data
• determine mean, mode and median of grouped and ungrouped data
• represent data using histograms and frequency polygons
• interpret data from histograms and frequency polygons
• promote data collection, organisation and representation for informed decision making

“What is statistics?”

“How do we represent data?”

“How do we use statistics in day-to-day life?”

The titles are open to everyone. Reading a lesson needs an account — sign in or create one.

1. What statistics is
   40 min · 1 practice tasks · quiz
   What data is, the four stages from raw figures to a decision, and why the last stage is the point of the other three.
2. Primary and secondary data
   40 min · 1 practice tasks · quiz
   Where figures come from, the advantages and drawbacks of each source, and the four questions to ask of anybody else's data.
3. Methods of collecting data
   40 min · 1 practice tasks · quiz
   Five collection methods, what each suits, and how to write a question that does not lead the answer.
4. Types of data
   40 min · 1 practice tasks · quiz
   Qualitative and quantitative, discrete and continuous, and why the type decides what you may calculate.
5. A frequency table for ungrouped data
   40 min · 1 practice tasks · quiz
   Tallying raw values into a frequency distribution table, and the check that catches a miscount.
6. Mode and median of ungrouped data
   40 min · 1 practice tasks · quiz
   Finding the value that occurs most often and the value in the middle, and what to do when n is even.
7. Mean of ungrouped data
   40 min · 1 practice tasks · quiz
   Adding and dividing, the mean as a balance point, and why a mean need not be a value that occurs.
8. Mean from a frequency table
   40 min · 1 practice tasks · quiz
   The fx column, why it is only a shortcut for repeated addition, and the checks that catch mistakes.
9. Grouping data into classes
   40 min · 1 practice tasks · quiz
   Why large data sets are grouped, how to choose sensible classes, and what grouping gains and costs.
10. Class limits, boundaries, width and midpoint
    40 min · 1 practice tasks · quiz
    The four numbers that describe a class, why boundaries sit half a unit outside the stated limits, and why it matters.
11. Modal class and the mean of grouped data
    40 min · 1 practice tasks · quiz
    Reading the modal class, estimating the mean using midpoints, and why the answer is an estimate.
12. Median of grouped data
    40 min · 1 practice tasks · quiz
    Cumulative frequency, locating the median class, and the interpolation formula with each symbol explained.
13. Histograms with equal class widths
    40 min · 1 practice tasks · quiz
    Drawing a histogram against class boundaries, and the differences between a histogram and a bar chart.
14. Histograms with unequal class widths
    40 min · 1 practice tasks · quiz
    Frequency density, why area rather than height represents frequency, and what goes wrong if you ignore it.
15. Frequency polygons
    40 min · 1 practice tasks · quiz
    Plotting at midpoints, closing the polygon at each end, and why polygons are better than histograms for comparison.
16. Interpreting data, and the statistics project
    40 min · 1 practice tasks · quiz
    Reading the shape of a distribution, writing an honest conclusion, and carrying out the KICD project.