1. Did people do what they said
Did people do what they said? Martin Boon, ICM Research John Curtice, University of Strathclyde

2. Did people do what they said?
Recap: The ICM method
All ICM Vote Intention polls employ a telephone method.
Representative samples of around 1,000 people each time, although the final prediction poll in 2010 interviewed just over 2,000 people.
Various weighting and adjustment procedures are employed, including:
Weighting by likelihood to turnout.
Weighting by recall of past voting, with target weights being 20% to the actual result of the previous General Election, and 80% to the average recall generated across (up to) the previous 25 ICM vote intention polls.
Adjustment procedure: reallocating 50% of the Dks and Partial Refusers back to the party they voted for in the previous General Election.
Did people do what they said?

3. Recap: The ICM performance
Con %
Lab LD
Other
Average error
ICM 36 28 26 10
1.25
Harris 35 29 27
1.5
Ipsos-MORI 8
1.75
Populus 37 11
ComRes 7
2.25
You Gov 9
Result 30 24 -
Did people do what they said?

4. ICM Polls: campaign tracking:
1. ICM cannot escape ‘Lib Dem surge’ issues.
2. Penultimate poll would have been pretty poor (AE: 2.75%)
3. All adds up to a need to test the efficacy of our methods.
Did people do what they said?

5. Did people do what they said?
The Recall Poll
ICM has conducted a Recall Poll after every election since It has been used to evaluate various conditions that affect past vote recall, including the tendency of LD voters to be somewhat more forgetful.
Certainly, the behaviour of Liberal Democrat supporters is in the firing line of our efforts on this occasion.
On this occasion we called back 4,662 people who had previously been interviewed on one of our campaign polls up to and including (original) poll fieldwork on April 14th 2010.
14-16th
Apr
17-23rd
24th-30th
1st-3rd
May
4th May Prediction Poll
Total
814
1,018
1,104
594
1,132
4,662
Did people do what they said?

6. Did people do what they said?
What we can examine
How well did people forecast whether they would vote or not?
What happened to the “Don’t Knows” and “Won’t Says”?
Was there a late swing?
Did people do what they said?

7. Did people do what they said?
Potential Pitfalls
Those who participated in the recall exercise may not be representative of all those who participated (sample is skewed towards older and middle class people)
In particular they may have been particularly likely to have voted (84% did so)
Some of the “Don’t Knows” and “Won’t Says” wouldn’t say afterwards either! (14% of voters didn’t declare their party id)
Not all respondents were originally interviewed close to polling day. The swing amongst those whose reported vote did not match their vote intention may not have been ‘late’ (46% interviewed before the last week)
Did people do what they said?

8. Did people do what they said?
Some Decisions
Data weighted to be demographically representative (but not past vote weighted)
In analysis of reported vote, those who failed to say for whom they voted are excluded.
Some analyses based only on those interviewed in the last week.
Did people do what they said?

9. Anticipated and Actual Turnout
Did people do what they said?

10. Estimating The Party Differential
Vote Intention
Estimated
Turnout
Actual
Gap
Conservative 95 92 +3
Labour 93 86 +7
Liberal Democrat 90 +2
Other 88 75
+13
Did people do what they said?

11. Alternative Estimates
Voting Intention
7-10 Only
Gap
3 point scale
Conservative 95 +3 90 -2
Labour +4 88 +2
Liberal Democrat 87 -3
Other 84 +9
Did people do what they said?

12. Did people do what they said?
Too big to ignore?
68% of those who did not declare a vote intention reported having voted.
These constituted 29% of all those who reported having voted…
Including 22% of those who voted who revealed for whom they voted.
Did people do what they said?

13. Did people do what they said?
A Distinctive Group
Did people do what they said?

14. Did people do what they said?
Their Recall of 2005
Did people do what they said?

15. How Recall 2005 Vote Anticipates Reported 2010 Vote
Con
Lab
Lib Dem
Other
DNV 66 14 15 17 7 48 12 13 10 54 24 9 4 3 8 28 2 20 11 70
Did people do what they said?

16. Did people do what they said?
Campaign and After
Did people do what they said?

17. Did people do what they said?
The Last Week and After
Did people do what they said?

18. Did people do what they said?
The Last Poll and After
Did people do what they said?

19. The (Last Week) Crossbreak
Con
Lab
Lib Dem
Other 87 1 4 7 2 80 3 78 8 * 54
DNV 15 9 27
Did people do what they said?

20. Did people do what they said?
Conclusion
Some differential abstention that was only partly captured by turnout weighting.
Labour profited – including relative to the Lib Dems - from the ‘shy Tory’ phenomenon – though this was (adequately?) allowed for in some polls.
But no convincing evidence of a significant late swing away from the Lib Dems.
So also need to look to possibility of sampling bias – or weighting error?
Did people do what they said?