Erection Research --Method: Participants

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Method

Participants

This study consisted of two overlapping phases. In the first phase, new data were collected to be analyzed later in parallel with Kinsey Institute data. Like the Kinsey samples, the new group (hereafter called the "photo sample") was not drawn by a precise sampling method. However, when the 81 subjects of the photo sample were compared with the population estimates from the US Census Bureau⁷ for 1992, the mean for the present photo study sample was found to be 40.4 years—almost identical to the estimated mean census age of 40.2 years for men between 20 and 69. (Based on ethical considerations, we chose not to use photography to study subjects younger than age 20.) Because of the propitiously matched age means, we accepted the 1992 US Census estimates for ages 20 to 69 as the template for our sample. As seen in Table 1, the present sample moderately approximated the census distribution by decades of age—although it was slightly more clustered toward the center. We made an effort toward the end of the study to find volunteers for the underrepresented age spans; still, the final sample contained 8.1% and 4.1% fewer men in their 20s and 60s respectively and 8.1% more in their 30s when compared to the census estimates.

TABLE 1. **Census Estimates Compared** **with Photo Sample**
Age	^{per cent of men aged 20-69}
Age	U.S. Census 1992 estimates⁷	Photo sample (n=81)
20-29	25.4	17.3
30-39	27.7	35.8
40-49	21.5	23.5
50-59	13.9	16.0
60-69	11.5	7.4
Total	100%	100%

In the second phase of the study, extant data of The Kinsey Institute were analyzed. As is their policy, the Institute staff conducted the primary analyses in-house following the specifications of the investigator. To obtain the largest numbers for the analyses, these data sets were aggregated. See Table 2.

TABLE 2. **Kinsey Samples Aggregated**
Kinsey sample	n
White male, non-college, original sample	1,093
White male, college, original sample	5,009
Black male, non-delinquent, original sample	519
White male, delinquent	2,446
Black male, delinquent	798
Total	9,865

This group (mean age = 29.1 years) was heavily weighted toward individuals in their teens (16.3%), twenties (47.9%), and thirties (20.0%)—although there were representatives of a wide span of ages including, for example, 1.3% in their 60s and 0.1% in their 80s. This distribution seemed too weighted toward younger ages to be an ideal reference group for general therapy clients. So we drew from the total group the largest possible sample (n = 1,484, mean age = 39.8, hereafter called the "Kinsey census sample") that would conform to the 1992 US Census Bureau estimates of percentages of men, by decades of age, from 20 to 69 years.

Subjects in the photo sample were from two sources. Newspaper ads were used to recruit 24 subjects in central North Carolina. An additional 57 were recruited at the 1994 and 1995 meetings of Gay Naturists International held in Pennsylvania. For the photo subjects we used volunteers, with all the potential bias this involves, because we felt systematic sampling was not possible with our limited resources. The lack of a sample which can be considered representative of a known population is a primary weakness of the present study—and of all the other erection research. From the outset, we acknowledge that inferences drawn from our photo sample to the general population of males or to any particular population must be tentative at best.

The 81 individuals who comprised the total photo sample were between 21 and 67 years of age. Their education varied from 12 (high school diploma) to 20 years (Ph.D.). The height of the subjects was from 5'4" to 6'6" and their weight ranged from 115 to 300 pounds. They were mostly white but included 3 African Americans, 2 Asian Americans, 1 Hispanic American, and 1 Native American.