Bringing data to life -statistical approaches to global issues 11-14 years Session 3 Add notes about what the lesson is about or background info about any photos (optional).

Using collective action groups to understand measures of central tendency Add notes about what the lesson is about or background info about any photos (optional).

What kinds of information about the women who belonged to collective action groups would it be interesting to compare?

The accountant of a honey cooperative weighs honey delivered by cooperative member. The honey will be bought by the cooperative, processed, then sold on to consumers. This photo will help bring to life that this was a real project working with real women in Ethiopia. Photo credit: Tom Pietrasik/Oxfam

Women filtering honey at their cooperative to remove wax and impurities. These women also produce honey themselves. This photo will help bring to life that this was a real project working with real women in Ethiopia. Photo credit: Tom Pietrasik/Oxfam

Discuss What is a measure of central tendency, also known as an average? Why might we use an average rather than look at a full data set? Is it possible to calculate averages for all the areas we came up with? The third bullet point refers to the question asked on slide 3.

Mean, median and mode Mean = this is the total of the numbers divided by how many numbers there are. Median = this is the middle value. Mode = this is the value that appears most often. To add extra detail and clarification to the definition of the median – Numbers should be placed in numerical order. For an odd amount of numbers, the median is the middle number. For an even amount of numbers, the median is the mean of the two central numbers.

Frequency diagram using un-grouped data Units of honey produced This is the data for a random sample of 100 women from the study. Ask learners how useful this graph is. The x axis shows individual women. How could we make this graph clearer?

Honey production in Ethiopia The above table shows units of honey produced by women farmer members of collective action groups.

Grouped frequency diagram for honey production Units of honey produced (kg) Frequency chart showing data for Ethiopian honey production (producers between 1 unit and 100 units. This data excludes non-producers (12) and producers of more than 100 units (13) – to make the graph more appropriate for this age group to interpret. Add explanation – data removed! Number of women farmers

Estimating the mean from grouped frequency data We know how many women fall into each grouped category. We can assume those women are all at the mid-point of the category (if we chose the lowest point, or highest point it would likely skew our estimate to being too big or too small – hence, we choose the mid-point). Multiply the mid-point by the frequency (number of women in that category). You need to do this for each category. Now add together the result for each category. Divide this by the total frequency (number of women in total). The final number is your estimate of the mean.

Amount Produced - Non-Group Member Minimum Mean Median Maximum 1.00 23.62 15.00 300.00 Amount Produced - Group Member 40.22 30.00 500.00 % Marketed - Non-Group Member 10.00 93.90 100.00 % Marketed - Group Member 12.50 94.05 What does this mean and median data tell us about collective action groups?

Years of Education - Non-Group Member Minimum Mean Median Maximum 0.00 0.32 10.00 Years of Education - Group Member 1.31 12.00 Wealth Index - Non-Group Member 37.09 36.27 79.61 Wealth Index - Group Member 5.85 37.37 35.76 100.00 What does this mean and median data tell us about collective action groups?

What do the averages tell us about the collective action groups? Write a short paragraph explaining what you have learnt. For example: The means of ……. tells me that group members ……. compared to those not in groups. The mode of …… is …. , this tells me that ………