REFERENDUM 2009 RESULTS: IRELAND ON LISBON TREATY

A note by Eamon Henry. 8 October 2009

This short discussion offers a statistical (regression) analysis of the Irish (2 October 2009) Referendum results, of voting for the second time on the Lisbon Treaty. For a turnout of 58.0 percent, there was a YES vote of 67.1 percent of turnout, implying a NO vote of 32.9 percent. For results of the 12 June 2008 Referendum, see the Henry article on http://www.asits.blogspot.com/ , of title “Referendum Results, Actual and Possible”.

Readers not familiar with statistical analysis are asked to accept “on faith” the results presented below via “Simple Regression” analysis of YES percentage as depending on TURNOUT percentage across all 43 constituencies.

The next paragraph gives results in technical format.

There follows a non-technical discussion.

The actual Yes and Turnout percentages, by constituency, are given as an appendix table below, having been extracted by me from the Irish Times of 5 October 2009. The “Data Desk” software package has been used by me to give the regression results and a graph.
Of all 43 constituencies, only two gave a NO percentage result above 50, namely Donegal North East and Donegal South West.

The regression results are as follows and rather technical. For a fairly loose-fitting “Rsquared adjusted” of 15.8 percent, a highly significant (99.5 percent probable) positive coefficient emerged, namely an average 0.758 percent Yes extra for every 1 percent extra turnout. This coefficient has a “standard error” of 0.254. The regression constant has value 22.58 (not significant) with its standard error of value 14.78.
We can estimate a YES percent value on the line of regression as follows. For a turnout of 50 percent, the regression estimate of YES percentage is given by constant plus 50 times the regression coefficient, namely 22.58 + 50X0.758 = 22.58 + 37.90 = 60.48 percent YES. A further 8 percent turnout, to match the actual, would add a further 8X0.758 = 6.06 percent Yes, thus giving a regression estimate of 66.54 percent Yes, close to the actual 67.1 percent quoted in the first paragraph above.

It is of interest to quote corresponding results of the Referendum of 12 June 2008. For a turnout of 53.1 percent of the electorate, there was a Yes vote of only 46.6 percent. Similar regression analysis gave an “Rsquared adjusted” of 13.0 percent, a highly significant (99 percent probable) positive coefficient 0.779 percent extra YES for every 1 percent extra Turnout. This coefficient had a “standard error” of value 0.289. The regression constant had value 4.66 (not significant) with standard error of value 15.39. We may note that the coefficient here is close to the October 2009 value 0.758 quoted above, but the constant here is much smaller (some 18 percentage points) than that of October 2009.
Here again we can estimate a Yes percentage on the line of regression. For a turnout of 50 percent, the regression estimate of YES percentage is given by constant plus 50 times the regression coefficient, namely 4.66 + 50X0.779 = 4.66 + 38.95 = 43.61 percent YES. A further 3.1 percent turnout, to match the actual, would add a further 3.1X0.779 =2.41 percent Yes, thus giving a regression estimate of 46.02 percent Yes, close to the actual 46.6 percent Yes quoted in the last paragraph above.

Appendix Table of Constituency Results, 2 October 2009

Constituency ---------Percent Turnout ------------Percent YES
Carlow-Kilkenny ---------------57.7---------------------------- 70.5

Cavan-Monaghan-------------- 58.1 ----------------------------62.0
Clare ---------------------------56.1---------------------------- 72.3
Cork East ----------------------56.6---------------------------- 66.1
Cork North Central -------------59.6 ----------------------------55.8
Cork North West--------------- 59.4---------------------------- 69.5
Cork South Central------------- 60.3---------------------------- 66.8
Cork South West ----------------59.5 ----------------------------67.2
Donegal North East -------------50.1 ----------------------------48.5
Donegal South West -------------51.1 ---------------------------49.7
Dublin Central ------------------53.3 ---------------------------61.9
Dublin Mid West ----------------55.3 ---------------------------61.5
Dublin North --------------------60.9--------------------------- 72.7
Dublin North Central------------ 65.6 ----------------------------71.1
Dublin North East ---------------63.4 ---------------------------63.5
Dublin North West --------------57.6---------------------------- 55.0
Dublin South --------------------57.6 ----------------------------81.7
Dublin South West --------------57.2 ----------------------------58.9
Dublin South Central ------------55.5 ----------------------------58.0
Dublin South East ---------------54.7---------------------------- 78.7
Dublin West ---------------------59.1 ----------------------------68.5
Dun Laoghaire------------------- 70.7 ----------------------------81.2
Galway East ---------------------54.8 ----------------------------68.1
Galway West --------------------53.1 -----------------------------66.3
Kerry North ---------------------55.4 ----------------------------63.6
Kerry South--------------------- 57.9---------------------------- 66.4
Kildare North --------------------56.6 ----------------------------76.2
Kildare South-------------------- 54.3 -----------------------------69.7
Laois-Offaly ---------------------57.5 -----------------------------73.2
Limerick East --------------------56.5 ----------------------------67.4
Limerick West -------------------56.2---------------------------- 69.3
Longford-Westmeath ------------55.4---------------------------- 65.6
Louth ----------------------------58.2 ----------------------------61.0
Mayo ----------------------------56.2 ----------------------------61.7
Meath East -----------------------54.9 ----------------------------72.3
Meath West---------------------- 60.5 ----------------------------64.9
Roscommon-SthLeitrim--------- 65.0 -----------------------------66.0
Sligo-NorthLeitrim --------------57.7------------------------------- 64.5
Tipperary North -----------------63.5 -----------------------------70.4
Tipperary South -----------------59.6 -----------------------------68.4
Waterford -----------------------59.6 -----------------------------68.5
Wexford -------------------------57.3 ------------------------------65.2
Wicklow -------------------------64.3 -------------------------------70.7