The statistics appearing on this page were based on data published in the following studies by the Pew Research Center:
- "The World's Muslims: Religion, Politics and Society." Pew Research Center. April 30, 2013. Available here.
- "The World's Muslims: Unity and Diversity." Pew Research Center. August 9, 2012. Available here.
- "The Global Divide on Homosexuality." Pew Research Center. June 4, 2013. Available here.
The following was also used as a reference:
- John Esposito and Dalia Mogahed. "Who Speaks for Islam? What a Billion Muslims Really Think." Gallup Press, 2008.
Information concerning the total size of a country's population and the total percentage of Muslims within it was needed to calculate many of the statistics above, and this was taken from the CIA World Factbook (here). In the few cases where the CIA World Factbook gave a range for belief in Islam as a percentage of the total population (e.g. 10-15%), a middle value was used (e.g. 12.5%).
Note that the percentages don't total to 100% in most of the graphs because it was possible for someone to say they didn't know, to offer a different answer than those that the surveys were prepared for, or to refuse to answer a question. Also note that in some cases administrative error by Pew meant that the data for some countries was lost, and that in other cases particular questions were not asked in Sub-Saharan Africa as a region. More information about the sample sizes and the margins of error can be found in the Pew publications themselves, along with information concerning the methodology employed and difficulties encountered. In the case of the 2013 publication, however, the sample sizes varied by country—anywhere from 551 in Lebanon to 1918 in Bangladesh—with margins of error hovering roughly around ± 5 points for each country.
When interpreting the numbers on this page, be weary that the fact that a belief or value x exists for a given subset of Muslims does not by itself show that Islam is wholly or even partly responsible for that being the case. For example, the fact that 43% of 1182 million Muslims believe in witchcraft does not necessitate that Islam is part of the causal explanation (any more than the fact that x percentage of Muslims use Facebook necessitates that Islam is part of the reason why). In themselves, the statistics on this page say what is the case, not why, and it requires assumptions to infer a connection.
Be also aware that someone might respond to a question with a particular answer not because they genuinely believe it, but because they think that is how they should answer it. For example, a Catholic might answer that they believe the bread and wine in communion literally transform into the flesh and blood of Christ not because they actually believe it does, but because they believe they should believe such things. (And keep in mind that the interviews carried out by Pew would often be conducted in front of one's family members in the family home.) Polls like those carried out by Pew find answers based upon what people report believing, not what they genuinely believe, and the two needn't be the same.
Finally, the statistics on this page were gathered from samples that represent anywhere from 0.9 to 1.2 billion of the world's Muslims (with the value varying by the particular question asked). While this is more than half of the world's Muslims, it is not all of them, and one must recognize that the totality of the views of the others (in Europe, America, India, Iran, Saudi Arabia, and elsewhere) may or may not align with what is set out above.