Statistically significant difference simply means there is statistical evidence that there is a difference. Statistically significant difference does not mean the difference is large, important or significant in the usual sense of the word.

When researchers study within groups or between group differences, they need a technique to determine if this difference would have occurred by chance. Various statistical techniques can determine this and if it is unlikely the differences could have occurred by chance it is called a statistically significant difference.

Small and non-notable differences can be found to be a statistically significant difference. Statistically significant result is not always of practical significance.

Usually a .05 level of significance is used (there are 5 chances of one hundred trials that this difference would occur by chance) but other levels can be used. When a researcher finds no statistically significant difference and writes as follows:

"we found no statistically significant difference," he could be misquoted as "they found that there was no statistically significant difference."

**What is the probability of
replicating a statistically significant difference effect?**

Jeff Miller, University of Otago, Dunedin, New Zealand

Abstract: If an initial experiment produces a statistically significant effect, what is
the probability that this effect will be replicated in a follow-up experiment? I argue
that this seemingly fundamental question can be interpreted in two very different ways and
that its answer is, in practice, virtually unknowable under either interpretation.
Although the data from an initial experiment can be used to estimate one type of
replication probability, this estimate will rarely be precise enough to be of any use. The
other type of replication probability is also unknowable, because it depends on unknown
aspects of the research context. Thus, although it would be nice to know the probability
of replicating a significant effect, researchers must accept the fact that they generally
cannot determine this information, whichever type of replication probability they seek.

**The Orthopaedic Trauma Literature: An Evaluation
of Statistically Significant Findings in Orthopaedic Trauma Randomized Trials** -
Jinsil Sung; Judith Siegel; Paul Tornetta; Mohit Bhandari

Abstract: Evidence-based medicine posits that health care research is founded upon
clinically important differences in patient centered outcomes. Statistically significant
differences between two treatments may not necessarily reflect a clinically important
difference. We aimed to quantify the sample sizes and magnitude of treatment effects in a
review of orthopaedic randomized trials with statistically significant findings.

**Association between industry funding and statistically significant pro-industry
findings in medical and surgical randomized trials **- Mohit Bhandari, Jason W.
Busse, Dianne Jackowski, Victor M. Montori, Holger Sch�nemann, Sheila Sprague, Derek
Mears, Emil H. Schemitsch, Dianne Heels-Ansdell and P.J. Devereaux

Conflicting reports exist in the medical literature regarding the association between
industry funding and published research findings. In this study, we examine the
association between industry funding and the statistical significance difference in results of
recently published medical and surgical trials.

**Gender Has a Small but Statistically Significant Difference Effect on Clearance of CYP3A
Substrate Drugs** - David J. Greenblatt, MD and Lisa L. von Moltke, MD

Address for reprints: David J. Greenblatt, MD, Department of Pharmacology and Experimental
Therapeutics, Tufts University School of Medicine, 136 Harrison Ave, Boston

From the Department of Pharmacology and Experimental Therapeutics, Tufts University School
of Medicine and Tufts Medical Center, Boston, Massachusetts. Dr. Hartmut Derendorf acted
as editor for this article.

The role of gender on the disposition of drugs metabolized by cytochrome P4503A (CYP3A)
remains controversial. Some sources suggest that CYP3A activity in women exceeds that in
men, but evidence to support this position is inconsistent at best. It was found that
gender has a small and statistically significant, although most likely clinically
unimportant, influence on CYP3A phenotype for substrates not transported by P-gp.

**ELISA: Structure-Function Inferences based on statistically significant and
evolutionarily inspired observations**

Boris E Shakhnovich, John M Harvey, Steve Comeau, David Lorenz, Charles DeLisi

BioInformatics Program, Boston University, Boston, MA, 02215, USA

Eugene Shakhnovich, Department of Chemistry and Chemical Biology, Harvard University

Abstract: The problem of functional annotation based on homology modeling is primary to
current bioinformatics research. Researchers have noted regularities in sequence,
structure and even chromosome organization that allow valid functional cross-annotation.