Page 327 - Encyclopedia of Nursing Research

294 n MIDDLE-RANGE THEORIES

Approaches are available to examine and nursing. Since then, meta-analyses have been
reduce bias from operating within a meta- conducted and published in a wide variety
M analysis. Some ways that biased conclusions of areas, such as patient outcomes of nurse
can occur in a meta-analysis are effects of practitioners and nurse midwives, job satis-
a bias toward publishing positive but not faction and turnover among nurses, relation-
negative results, giving each study an equal ship between postpartum depression and
weight in the meta-analysis despite the fact maternal–infant interaction, effects of educa-
they differ in sample size or quality, inclusion tional interventions in diabetes care, quality
of multiple tests of a hypothesis from an indi- of life in cardiac patients, and nonnutritive
vidual study, and not ensuring an acceptable sucking in preterm infants.
level of agreement or reliability among raters The outcome of this quantitative
in coding the study characteristics. approach for reviewing the literature has
It can be argued that not all studies syn- tremendous potential for a practice-based
thesized in a meta-analysis should be given discipline such as nursing. Meta-analysis of
equal weight. Some studies may be poorly the abundance of research being conducted
designed and have small unrepresentative can benefit nursing practice. Not only will
samples, whereas other studies use random- the use of meta-analysis further knowledge
ized control group designs with large sample development in the discipline of nursing, but
sizes. To remedy this problem, studies can be it also can help nurses in the clinical setting
evaluated and assigned a quality score. The to decide whether to apply research findings
meta-analysis can then be calculated with to their practice based on the size of the dif-
studies weighted by their quality scores. ference an intervention makes. Meta-analysis
A source of nonindependence in a meta- can resolve issues in nursing where there are
analysis can result from using multiple multiple studies with conflicting findings. In
hypothesis tests based on multiple variable addition, meta-analysis highlights gaps in
measurements obtained from a single study nursing research for future studies.
(Strube & Hartman, 1983). One suggested
remedy when selecting findings obtained Cheryl Tatano Beck
from multiple measures of the hypothesis
tests located within a single study is to col-
lapse the various findings into a single, global
hypothesis test. Middle-range theories
One assumption that should be met
before specific studies are quantitatively
combined in one meta-analysis is that each Middle-range theories are described by
study provides sample estimates of the effect Merton (1968, p. 9) as those that “lie between
sizes that are representative of the popula- the minor but necessary working hypoth-
tion effect size. Homogeneity tests can be eses that evolve in abundance during day-
calculated to identify any outlier studies. If to-day research and the all-inclusive sys-
outliers are identified, they can be removed. tematic efforts to develop unified theory.”
Meta-analysis first appeared in the nurs- He goes on to say that the principal ideas of
ing literature in 1982, when O’Flynn published middle-range theories are relatively simple.
her article describing meta-analysis in the Simple here means rudimentary, straightfor-
“Methodology Corner” of Nursing Research. ward ideas that stem from the focus of the
A meta-analysis of the effects of psychoedu- discipline. Thus, middle-range theory is a
cational interventions on length of postsur- basic, usable structure of ideas, less abstract
gical hospital stay (Devine & Cook, 1983) was than grand theory and more abstract than
the first meta-study analysis published in empirical generalizations or microrange