County Descriptive Statistics by LCMS Percentage Change Increase or Decrease and Absolute Number Increase or Decrease, 1971-2010 Number of Counties
% of Population Increase
% of Population Decrease
Total Adherent Increase
Total Adherent Decrease
516
1337
798
1053
Mean Total Population
69914.5
1711891.7
121308.1
160527.8
Mean LCMS Change in Number of Adherents
254.9
-479.7
359.5
-756.6
Mean % White
90.8
89.0
90.3
89.0
Mean % Black
5.8
6.8
6.0
6.8
Mean % Asian
0.9
1.4
1.1
1.4
Mean % Hispanic
5.5
8.9
7.1
8.6
Mean % German-American
20.2
19.6
18.4
20.9
% Lost Pop. 2000-2009
0.4
0.4
0.2
0.5
Mean % of Women that Gave Birth in Past Year
5.6
5.6
5.5
5.7
Mean Median Age
39.1
38.3
37.9
38.9
Mean % Unemployed
8.5
9.0
9.1
8.7
% Employed in Agriculture
8.5
6.9
5.9
8.4
Mean % Rural
57.1
47.2
49.3
50.4
It is encouraging to see that there are a large number of counties where the LCMS has grown, both as a percentage of the population and in absolute numbers — even if the number of counties where the LCMS is on the decline is larger. However, in counties where the LCMS has grown, the total increase is much smaller than the total decrease in counties where the LCMS population has become smaller. In counties where the absolute number of LCMS adherents is now larger than it was in 1971, the mean total increase was about 360 people. In counties where the number of adherents declined, the mean decrease was about 757 — or more than twice as large. It is interesting to note that we do not see a dramatic difference between the county types on other important variables. We see that counties where the LCMS is on the decline are slightly more Hispanic, but otherwise, most of these other variables would be in the margin of error.
A Statistical Model of the LCMS as a Percentage of County Population: The Importance of German Ancestry A problem with drawing inferences from descriptive statistics alone is that many of the variables we have considered are correlated with each other, sometimes strongly. This can make it difficult to discern the precise effect that one variable has on another. Multiple regression is a common solution to this problem, as it allows the researcher to isolate the effect of a specific independent variable on the dependent variable while controlling for all other variables in the model.
In order to draw correct inferences from a regression model, a number of assumptions must hold. Some models are more prone to problems and biases than others. When working with geographic data (in this case, counties), there is particular concern with the issue of spatial autocorrelation. As a result, more sophisticated methods are necessary. See the statistical appendix of this chapter for a detailed description of the model and related issues, and the steps taken to resolve them. The interpretation of the county-level model, however, can be found below. From the statistical model, we see that a number of variables that were modestly correlated with the percentage of a county that was associated with the LCMS had no statistically significant effects on the LCMS population in 2010 after controlling for other variables.4 For example, the percentage of a county that voted for McCain in 2008 was not statistically significant or substantively important. In other words, it does not appear to be the case that a county’s aggregate political conservatism had an effect on LCMS membership, one way or the other. We also see that the percentage of a county that was rural had no discernible effect. The same was true for the dichotomous variable indicating population loss in the subsequent decade. The unemployment rate and the total population size were similarly insignificant. 4
The concept of statistical significance is somewhat complicated, and subject to much discussion and debate. For readers not familiar with this term, it is sufficient for our purposes to state that a variable has achieved statistical significance if it is very unlikely that the effects we see in our model were due to chance alone.
Journal of Lutheran Mission | The Lutheran Church—Missouri Synod
47