Passage: According to the constitution, the state language of Ukraine is Ukrainian. Russian is widely spoken, especially in eastern and southern Ukraine. According to the 2001 census, 67.5 percent of the population declared Ukrainian as their native language and 29.6 percent declared Russian. Most native Ukrainian speakers know Russian as a second language. Russian was the de facto official language of the Soviet Union but both Russian and Ukrainian were official languages in the Soviet Union and in the schools of the Ukrainian SSR learning Ukrainian was mandatory. Effective in August 2012, a new law on regional languages entitles any local language spoken by at least a 10 percent minority be declared official within that area. Russian was within weeks declared as a regional language in several southern and eastern oblasts (provinces) and cities. Russian can now be used in these cities'/oblasts' administrative office work and documents. On 23 February 2014, following the 2014 Ukrainian revolution, the Ukrainian Parliament voted to repeal the law on regional languages, making Ukrainian the sole state language at all levels; however, the repeal was not signed by acting President Turchynov and current President Poroshenko. In February 2019, the law allowing for regional languages was found unconstitutional.Ukrainian is mainly spoken in western and central Ukraine. In western Ukraine, Ukrainian is also the dominant language in cities (such as Lviv). In central Ukraine, Ukrainian and Russian are both equally used in cities, with Russian being more common in Kiev, while Ukrainian is the dominant language in rural communities. In eastern and southern Ukraine, Russian is primarily used in cities, and Ukrainian is used in rural areas. These details result in a significant difference across different survey results, as even a small restating of a question switches responses of a significant group of people. Hungarian is spoken in the Zakarpattia Oblast.For a large part of the Soviet era, the number of Ukrainian speakers...

Question: What examination was used to measure responses?
survey