{"id":22968,"date":"2022-06-08T10:48:54","date_gmt":"2022-06-08T10:48:54","guid":{"rendered":"https:\/\/factcheckni.org\/?p=22968"},"modified":"2023-12-18T11:16:54","modified_gmt":"2023-12-18T11:16:54","slug":"when-is-40-3-not-higher-than-39-6%ef%bf%bc","status":"publish","type":"post","link":"https:\/\/factcheckni.org\/articles\/explainers\/when-is-40-3-not-higher-than-39-6%ef%bf%bc\/","title":{"rendered":"When is 40.3 not higher than 39.6?\ufffc"},"content":{"rendered":"\n
CLAIM: The nationalist vote in Northern Ireland has not increased since 1998.<\/strong><\/p>\n\n\n\n RATING: Accurate? Inaccurate? Neither? Maybe a little bit of everything?<\/strong><\/p>\n\n\n\n On May 18, DUP MLA Emma Little-Pengelly tweeted:<\/a> \u201cA gentle reminder, the nationalist vote has not increased since 1998.\u201d<\/p>\n\n\n\n She received the following reply:<\/p>\n\n\n\n <\/p>\n\n\n\n So, in the 1998 Assembly elections, the nationalist first preference vote share was 39.6%. In this May\u2019s elections, the share was 40.3% – therefore Ms Little-Pengelly was wrong?<\/p>\n\n\n\n Actually, not quite\u2026<\/p>\n\n\n\n Significance<\/strong><\/p>\n\n\n\n Statistical significance is the idea that some change in some specific data under different circumstances (including through the passage of time) is not a matter of coincidence.<\/p>\n\n\n\n In other words, the change is not simply random chance – what is sometimes called \u201cstatistical noise\u201d. Instead, the altered circumstances have very likely played a role in the change in data.<\/p>\n\n\n\n For example, if you plant 1,000 hardy perennial wildflowers in a field one year and the next year only 983 grow, you would not say that your wildflower meadow faces inevitable decline.<\/p>\n\n\n\n That\u2019s because it\u2019s unlikely that such a small reduction in blooms is statistically significant. Your meadow might <\/em>be doomed – you might have been freakishly lucky to get that many flowers in year two – but you wouldn\u2019t conclude that from the available information.<\/p>\n\n\n\n In 1998, the nationalist vote share was 39.6%. In 2022, it was 40.3%. This could stem from an upward trend in vote share over time. However, it absolutely could just be \u201cnoise\u201d.<\/p>\n\n\n\n A similar thing can be seen when considering the percentage of seats won by nationalist candidates in NI Assembly elections since 1998.<\/p>\n\n\n\n <\/p>\n\n\n\n Pic: From the BBC<\/em><\/a><\/p>\n\n\n\n You could point out the fact that the green line goes down and up, up and down. Or you could say it\u2019s basically flat and that all the variations are just noise, and not statistically significant.<\/p>\n\n\n\n If you want a more formal, more strictly accurate and more unwieldy explanation of statistical significance (featuring the null hypothesis, p-values, confidence intervals – all the hits) this primer from National Centre for Biotechnology Information in the USA<\/a> is about as clear as you are going to get.<\/p>\n\n\n\n Back to our own example, and Twitter\u2026<\/p>\n\n\n\n Not a Fact Check<\/strong><\/p>\n\n\n\n