Addressing common concerns raised about Twaweza’s opinion poll survey

Much of the discussion in traditional media, on social media and elsewhere regarding our recently published opinion poll findings on Tanzanian politics has focussed on perceived errors in the brief. We want to correct three of the most common misunderstandings.
1. “Totals do not add up to 100%.”
It has been pointed out that several charts and tables in the brief include data that does not seem to add up to 100%. In some cases, the figures add up to 99%, 101% or 102%.

This is purely as a result of rounding the figures to the nearest whole number, a standard practice in opinion poll research. We do this because presenting figures with one or even two decimal points suggests a level of precision in the findings that can be misleading.

The examples below show how this happens, by presenting the unrounded figures alongside the rounded figures that were presented in the brief.

For Figure 2a: Are you aware of the promises made by your MP?

	unrounded	rounded
Don't know	5.14%	5%
Yes	64.39%	64%
No	30.47%	30%
Total	100.00%	99%

For Figures 5b, 5c, 5d: If the election was held today, which political party’s candidate would you vote for? / Which political party do you feel closest to, if any?

	2015 MP (Figure 5b)		2015 councillor (Figure 5c)		2015 affiliation (Figure 5d)
	unrounded	rounded	unrounded	rounded	unrounded	rounded
CCM	60.4%	60%	59.9%	60%	61.9%	62%
Chadema	24.1%	24%	25.5%	26%	25.0%	25%
CUF	1.8%	2%	2.5%	3%	2.3%	2%
ACT-Wazalendo	1.4%	1%	0.6%	1%	0.7%	1%
NCCR Mageuzi	1.1%	1%	1.0%	1%	0.3%	0%
Ukawa*	2.8%	3%	2.6%	3%	2.1%	2%
Other	6.4%	6%	6.0%	6%	2.3%	2%
Don't know / no response	2.0%	2%	1.9%	2%	5.3%	5%
Total	100.0%	99%	100.0%	102%	100.0%	99%

For Figure 6b: Will Ukawa appear on the ballot paper during the

2015 elections?

	unrounded	rounded
Don’t know	17.6%	18%
No	25.7%	26%
Yes	56.7%	57%
Total	100.0%	101%

2. “Totals for 2013 and 2014 add up to much less than 100%.”In figures 5a-5d, some totals for years 2013 and 2014 add up to considerably less than 100%. This is a result of some responses being left off the chart because in this years’ survey nobody gave those responses. In particular, the response “I don’t vote for parties, I vote for candidates” was popular in previous years, but it was not mentioned in 2015. 
The complete numbers for these four charts are presented below. Figures that were not included in the brief are presented in italics. For 2015, both unrounded and rounded figures are shown.
For Figure 5a: If the election was held today, which political party’s candidate would you vote for? President

	2012	2013	2014	2015
				Unrounded	Rounded
CCM	61%	47%	51%	65.8%	66%
Chadema	30%	30%	23%	21.5%	22%
CUF	4%	4%	4%	0.5%	1%
ACT-Wazalendo	0%	0%	0%	0.2%	0%
NCCR Mageuzi	0%	1%	1%	0.2%	0%
Ukawa*	0%	0%	0%	3.3%	3%
Other	1%	2%	0%	6.3%	6%
Don't know / no response	4%	0%	4%	2.2%	2%
I don't vote for parties but candidates	0%	15%	16%	0.0%	0%
None	0%	1%	1%	0.0%	0%
Total	100%	100%	100%	100.0%	100%

For Figure 5b: If the election was held today, which political party’s candidate would you vote for? Member of Parliament

	2012	2013	2014	2015
				Unrounded	Rounded
CCM	60%	44%	46%	60.4%	60%
Chadema	31%	31%	24%	24.1%	24%
CUF	4%	4%	4%	1.8%	2%
ACT-Wazalendo	0%	0%	0%	1.4%	1%
NCCR Mageuzi	0%	1%	1%	1.1%	1%
Ukawa*	0%	0%	0%	2.8%	3%
Other	0%	2%	1%	6.4%	6%
Don't know / no response	5%	0%	5%	2.0%	2%
I don't vote for parties but candidates	0%	17%	18%	0.0%	0%
None	0%	1%	1%	0.0%	0%
Total	100%	100%	100%	100.0%	99%

For Figure 5c: If the election was held today, which political party’s candidate would you vote for? Councillor