In the article "Religious Differences Between Married and Celibate Clergy: Does Celibacy Make a Difference?" in Sociology of Religion (1998) (full text available to members of subscribing libraries or universities), Don Swenson attempts to make an empirical argument against some of the reasons advanced by the Church for clerical celibacy. While the experiment itself is poorly constructed to the point of being ludicrous, the idea is an interesting one, and I am of the opinion that this sort of empirical study could be profitably employed more within the Church (as it often is within large organizations).
Basically the idea of the study was to take a sample of married clergy and a sample of celibate clergy, measure devotion to Christ (religiosity) and the ability to devote oneself to parishioners, and see whether there is a significant statistical difference between the married and celibate clergy. Devotion to Christ was measured through responses made to questions about "thanking, talking to, loving, taking time with, worshiping, feeling close to and listening to God, reflecting on the Bible, acting on what I believe God is saying, achieving insights in prayer, sensing a divine presence, and experiencing peace" and the time spent in prayer. The ability to devote oneself to parishioners was measured by the amount of time spent in ministry.
The responses to the survey indicated that "there was no significant difference regarding MEDITATION [measuring religiosity and devotion to Christ] and PASTORAL COMMITMENT", while the priests spent more time in prayer and prayed more frequently than the married, evangelical clergy. The author argues that the "experiential religiosity" which the study aimed to measure is a better measure of devotion to Christ, and thus there was no significant difference between the two groups in terms of that devotion.
While the stated conclusion, "The results of this study are substantially consistent with the hypothesis that there are no significant differences in dimensions of religiosity and parochial commitments between celibate priests and married clergy" (emphasis added) is formally true, it is also true that the results of the study do not significantly support that hypothesis. The practical conclusion of the paper, "The implications of this study are that there is some empirical basis to argue for a change in the present law of clerical celibacy. In regards to one's devotional life and time for ministry, celibacy does not appear to matter" is therefore unwarranted. (Update: It was also pointed out in a comment that the study indicates that unmarried clergy spend more time in prayer and pray more frequently, and that this is itself in fact a reason for clergy to remain celibate, a point that the study ignored, as though prayer was of no value — or at least, that the question of prayer was basically irrelevant for the life of clergy.)
The study, in fact, has several glaring problems of which the author is apparently heedless. The two groups of clergy differed in multiple significant ways other than being celibate or married: (1) the one group was evangelical, the other Catholic (this was apparently the actual principle of division, since one group seems to have included all evangelical pastors, whether married or celibate). (2) One group (the evangelical) was taken as a sample from all over Canada, the other from only two dioceses. (3) The average age of the evangelical ministers was 44, while that of the priests was 60, a difference that the author points out, then proceeds to ignore. Lesser, though still significant problems, are that the response rate of priests was significantly lower than that of evangelical ministers, and that the total number of responses from priests was 80.
Was the author of the study clueless about what is necessary in order to establish a general statistical relationship? Or was he blinded by a bias with which he approached the study? It is not possible to say. But one thing is clear. If this kind of evidence is to be used to propose a change in the Latin or in the Oriental discipline, it should be collected much more soundly.