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Monday, July 9, 2012

Secularization in America: part five

Summary so far

In Part One I described trends in market share of major religions in the U.S.: since 1988, the fraction of Protestants dropped from 60% to 51%, and the fraction of people with no religious affiliation increased from 8% to 18%.

In Part Two I used data from the 1988 General Social Survey (GSS) to model transmission of religion from parent to child, and found that the model failed to predict the decrease in Protestants and the increase in Nones that occurred between 1988 and 2010.

In Part Three I looked at changes, between 1988 and 2008, in the spouse tables (which describe the tendencies of people to marry within their religions), the environment table (which describes parents' decisions about their children's religious upbringing), and the transmission table (which describes the likely outcomes for children raised within each religion).  I found that the transmission table has changed substantially since 1988, and accounts for a large part of the observed increase in Nones, but not the decrease in Protestants.

Part Four revisited

In Part Four I looked at changes in religiosity over the lifetime of respondents.  The GSS is not a longitudinal survey, so we can't follow individuals, but we can follow generations (which I partition by decade of birth) over time.

Last time I presented this figure, which shows religiosity (the fraction of respondents with any religious preference) as a function of respondent's age, partitioned by decade of birth, for people who were raised Protestant:

Each line represents a different generation.  For example, the red line shows that people born in the 1920s were about 96% likely to report a religious preference when they were interviewed in their 40s, 50s, and 60s, and possibly less likely to be religious when they were in their 80s.

The conclusion I drew from this figure is that the differences between generations are larger than the changes, over time, within each generation.  For purposes of modeling I concluded that religious disaffiliation accounts for only a small part of the observed changes in religious identity.

But I was bothered by one feature of these curves: many of them are concave down, and the maximum point in the curves is apparently shifting toward younger ages.  I came to suspect that this picture of the data is "out of focus".

We can refocus the image by plotting the date of the survey (rather than the respondent's age) on the x-axis.  Here's what that looks like:

In this figure, two trends are more apparent: before 1990, most generations were becoming more religious; after 1990, they all became less religious.  So it seems clear that the explanation is something that affected all generations at a particular interval in time, not something that affects all people as they age.

We can see these changes more clearly by normalizing each curve with its 1990 value:

Again, most generation were becoming more religious before 1990; after 1990, all of them became less religious.  Among people born in the 1960s, more than 10% lost their religion between 1990 and 2010 (when they were in their 30s and 40s).

Here's the same graph for people raised Catholic:

The general shape is the same: religious affiliation was flat or increasing prior to 1990, and decreasing for almost all generations after 1990.

Since the trends are similar for Catholics and Protestants, we can get a less noisy picture by combining them.  Here is the same graph for respondents raised with any religion.

This figures makes it easier to compare across generations.  It appears that more recent generations (born in the 1960s and 1970s) are disaffiliating at higher rates than earlier generations.

[As an aside, this result contradicts one of the primary (and widely-reported) claims of this article: Schwadel, Period and Cohort Effects on Religious Nonaffiliation and Religious Disaffiliation.  Schwadel reports that people born in the 1960s and 1970s were disaffiliating at a slower rate than the previous generations.  Some reasons my results might be different: Schwadel only had GSS data up to 2006, and he discards people under 30 years of age.  So very little data about the youngest generations is included.  Also, his results are based on statistical models that (if I understand correctly) don't include time as an explanatory variable, so they cannot account for an event that affects all generations during a particular interval.]

All right, it's audience participation time.  What happened in the 1990s that caused widespread religious disaffiliation?  Remember, idle speculations only.  No evidence, please!


  1. perhaps nothing happened in the 90s. and since most believers are partly foxhole believers, without major crises religiosity declines. world wars, financial depressions should ramp up religious belief.

    1. It is true that 90s was a time of prosperity, and since religion functions as ex-post insurance for a majority of people, religious participation decreases in good times. However, I don't think a catholic or a protestant will become disaffiliated as a result of good economy and peace. I would expect church attendance rates to fall for this reason, but not religious affiliation.

    2. Both our comments stem from intuition. Perhaps there is some way to test this theory. I tried to look for localized disasters during the 90s which would according to my hypothesis promote religiosity. The only thing I came up with is the 1987 L.A. quake. I do not have the local data, but perhaps Allen or someone else does. Maybe I am missing another obvious disaster. In any case I would expect levels of religiosity in L.A to decline less than the national average in the 1987-1990 period.
      To be more thorough, a discontinuity regression method could be used around a collection of disaster dates and locations.

  2. I think it was the advance of science, especially in the area of life sciences that disillusioned some people. 90s was a time of cloning and gene sequencing, these advances were right in the alley of God and I would imagine some people faced a crisis of faith after hearing about them. I would imagine the younger and better educated of these people to leave the church for good as a direct result of this crisis.

  3. Internet popularity spread in the 90's and millions were able to exchange ideas at a much faster rate.

  4. That's easy: In 1991, R.E.M. released the album "Out of Time", which included the hit song "Losing My Religion." Then, in 1995, after the previous year's strike had wiped out the World Series for the first time in 100 years, the Yankees returned to dominance after a decade and a half of irrelevance, thus proving conclusively that there is no god.

  5. Though the argument for the return of the Yankees is incontrovertible, I have to return to the underlying theory of the causal connection of Internet usage and religiosity: exposure to other ideas. Cable TV saturation? Will see if I can get some numbers from the cable cartel. (Maybe Blockbuster really peaked in 1995!) The Religious, I have to assume, too, know their market, and 'exposure' to other voices has always been frowned upon. May need to look at when Larry Flynt triumphed with his Hustler store right in the heart of Cincinnati.