Terms describing sexual behavior are used differently by different researchers, and the same terms are often used to describe different behaviors. Specifically, major problems arise with the varying definitions of "incest," "child-adult contact," and "abuse."

Incest 

The definition of incest in the studies reviewed range 

Thus, definitions vary, both with respect to the behavior and the partner. 

A further elaboration of this confusion is seen in the Meiselman review. Of the 47 studies cited in that review, 

Of the 19 studies involving incest which are reviewed in this paper, partners are described as "parental," "paternal," "sibling," or "other."

In regard to incestuous sexual behaviors, 

The concern here is that researchers are making generalizations about behaviors which may be too varied for such general conclusions to be valid. It is necessary to determine that outcomes are consistent across types of behaviors and different partners before such generalizations are appropriate and more sweeping definitions of incest are warranted.

Child-adult contact

Researchers focusing on "child-adult contacts" have also varied in their definitions of "adult" and "child." For example, some researchers referred to "parent-child relations," and some of these were so vague that the reader is unable to determine their definitions of child and adult. The majority did not specifically deal with this concern. Three researchers were concerned with the effect on children 

of relating to older sexual partners and, therefore, stated clear definitions. 

The concern here is the lack of specificity about ages studied. Researchers are again making generalizations about effects of behaviors which may be too varied for such conclusions. What is needed is for researchers to discriminate between the ages of the children studied and then look at the effects with partners of different ages.

Abuse

"Abuse" has been the catch-all term for almost any type of child-adult contact. However, other terms are used by researchers to refer to similar behaviors. 

The major issue here is whether the researcher has defined "abuse" as some type of harm (a consequence of sexual activity that can be quantitatively measured) or whether "'abuse" is defined in relation to violation of social norms. When the two issues of scientific objectivity and maintenance of moral standards are not separated, problems arise.

On the one hand, science is a pursuit to understand the world as it is. 
On the other hand, social norms are rules by which people choose to live. 
Failure to make a distinction between the two has caused many researchers to buttress existing social norms rather than to conduct 

 Sampling problems which surfaced were the lack of control groups, small number of cases, use of clinical populations, combining age groups, and combining socio-economic groups.

Lack of control groups

Only 10 of the 34 studies reviewed here used control groups. Seven of these have been published since 1978 (see Table 1). Without the use of control or comparison groups, it is impossible to determine causal effects or isolate contributing factors. 

Small number of cases 

Of the studies listed in Table 1, 

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All but 2 studies published since 1981 have used over 100 cases. This is, hopefully, an indication of a trend away from small descriptive case studies toward larger studies with the potential for more sophisticated analytic procedures.

Clinical and offender populations   

Seventy percent of the studies reviewed utilized clinical or offender populations. An example of the problems involved in using samples from this type of population is found in Meiselman (1978). She found a higher incidence of sexual problems of all types among patients with father-daughter incestuous experiences than among patients without incestuous experiences. If a  woman seeks help because she has problems in social functioning, and she is then selected for study because she has a history of certain childhood sexual experiences, it is impossible to determine whether the problems in social and personal functioning are due to the childhood sexual experiences or to all the other things that may lead to the problem being treated. 

Another problem with this type of study is that it is not known how these cases differ from a nonclinical population. 
The same point could be made for using offender populations. Primarily, it may tend to create bias and limit the generalizability to other populations.

Combining age groups 

Another problem occurs when studies in which the ages of the samples vary are combined and general conclusions are draw. The studies reviewed included samples from ages 1 to 77. Also, the interval between when the childhood sexual experience occurred and when the effects were studied varied from a few years to 50 years. 

Of particular concern is the combining of data on effects in pre-pubertal children with post-pubertal children. Some researchers have found that effects are much more critical after puberty 

(Mann & Gaynor, 1980; Sedney & Brooks, 1984; Sloane & Karpinski, 1942). 

In marked contrast, Rasmussen (1934) and Bender and Blau (1937) found pre-pubertal experiences more critical. Studies which compare long-term effects on these two age groups could be quite beneficial and revealing. However, when generalizations are made across these groups, important data may be lost and findings may be misleading.

Combining socio-economic groups 

There were 13 studies in which primarily lower-class samples were used. Six used primarily middle-class samples, 4 used middle- to upper-class samples, and 1 used a lower- to middle-class sample. Nine studies did not give the socio-economic groups used (in most of the studies many classes were sampled). 

Combining the findings across the range of socioeconomic 

The third problem encountered is the measures of consequences. 
For example, 

The lack of specificity in these studies is problematic. 

In some studies there was also a lack of specific data regarding the length of time between the experience itself and the measures of the so-called long-range effect 

(e.g. Greenland, 1958; James & Meyerding, 1977; Justice & Justice, 1979; Medlicott, 1967). 

Other researchers were very specific regarding the time span between the experiences and the study. 

Immediate effects are sometimes quite different from long-range effects, and it is important to distinguish between the two.

More recently, most authors have been more specific regarding the measure of long-range effects. 

A related issue with respect to the use of terms like "consequences" and "effects" is that these terms imply causal relationships between childhood sexual experiences and adult functioning. Such causal inferences are usually inappropriate given the retrospective and/or correlational nature of many of the studies. 
For example. there have been many reports that the social system's handling of incidents regarding sexual abuse of children caused as much or more harm as the sexual experience itself 

 (Brunold. 1964; De Francis, 1969; Justice & Justice, 1979; Mann & Gaynor, 1980; Schultz. 1973; Summit & Kryso. 1978). 

Effects or consequences attributed to the sexual experience itself may have actually been caused by the way the experience was handled by the social system. or, for that matter, by any number of other factors. Extreme caution must be exercised in claiming causal relationships.