I was listening to the following podcast from the BBC's "More Or Less", a radio programme about numbers, and I thought it was interesting and I should make a post about it. Warning: streaming the episode through the embed might have adverts. Clicking the link for the embed should download the episode if you're in the UK. If you're elsewhere, this link should download the episode. Probably.
Exercise: Using the data in the following table, calculate the percentage of votes received by each candidate. Assume that all votes are given in the table. Give your answer to 2 decimal places.
| Candidate | Number of Votes |
|---|---|
| William Ruto | 7,176,141 |
| Raila Odinga | 6,942,930 |
| George Wajackoyah | 61,969 |
| David Mwaure | 31,987 |
Answer
| Candidate | Number of Votes | Percentage (2 d.p.) |
|---|---|---|
| William Ruto | 7,176,141 | 50.49% |
| Raila Odinga | 6,942,930 | 48.85% |
| George Wajackoyah | 61,969 | 0.44% |
| David Mwaure | 31,987 | 0.23% |
| Total | 14,213,027 | ? |
William Ruto: 7,176,141/14,213,027≈0.504899≈50.49% (to 2 d.p.)
Raila Odinga: 6,942,930/14,213,027≈0.488491≈48.85% (to 2 d.p.)
George Wajackoyah: 61,969/14,213,027≈0.00436≈0.44% (to 2 d.p.)
David Mwaure: 31,987/14,213,027≈0.002251≈0.23% (to 2 d.p.)
Data Source
Rest of Post
So, when people looked at the results, summarised as percentages, they noticed something odd. If you add up the percentages, you get 50.49% + 48.85% + 0.44% + 0.23% = 100.01%. That's not possible! It should total 100% exactly! This is, of course, a very common error when interpreting rounded numbers. When a different quantity of numbers gets rounded up compared to down, you can end up with an incorrect total. This was seen by some people as evidence of irregularities, but if you look at the original numbers, you can see that it doesn't mean anything. If you round the same numbers to 1 decimal place, you would get the opposite result: they would total 99.9%.There were also other accusations of issues with the election. This included a reported turnout which was later changed from 65.4% to 64.6%. Despite this, since that podcast came out, the supreme court of Kenya has rejected the legal challenge to the result. William Ruto has now been sworn in as president, although Raila Odinga did not attend the ceremony and continues to doubt the legitimacy of the result.
So, what's the moral of the story? That's left as an exercise for the reader.