Abstract
Objective: To re-examine data on sperm counts over time from 61 studies from around the world. Design: Parametric analyses and flexible nonlinear models of the relation between sperm counts and time. Main Outcome Measure(s): Mean sperm concentrations per milliliter and regression coefficients for possible trends of concentrations over time. Result(s): A significant decline was found only in U.S. studies. Conclusion(s): Studies from specific sites have found declines in sperm counts, but a world-wide decline has not been demonstrated. Rigorous assessment of statistical models should be done before conclusions are drawn. Flexible smoothing models are a useful addition to currently available analytic methods.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1103-1108 |
| Number of pages | 6 |
| Journal | Fertility and Sterility |
| Volume | 67 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 1997 |
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Keywords
- Mean sperm counts
- Meta-analysis
- Statistical modeling
ASJC Scopus subject areas
- Obstetrics and Gynecology
Cite this
A meta-analysis of 61 sperm count studies revisited. / Becker, Stanley; Berhane, Kiros.
In: Fertility and Sterility, Vol. 67, No. 6, 06.1997, p. 1103-1108.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A meta-analysis of 61 sperm count studies revisited
AU - Becker, Stanley
AU - Berhane, Kiros
PY - 1997/6
Y1 - 1997/6
N2 - Objective: To re-examine data on sperm counts over time from 61 studies from around the world. Design: Parametric analyses and flexible nonlinear models of the relation between sperm counts and time. Main Outcome Measure(s): Mean sperm concentrations per milliliter and regression coefficients for possible trends of concentrations over time. Result(s): A significant decline was found only in U.S. studies. Conclusion(s): Studies from specific sites have found declines in sperm counts, but a world-wide decline has not been demonstrated. Rigorous assessment of statistical models should be done before conclusions are drawn. Flexible smoothing models are a useful addition to currently available analytic methods.
AB - Objective: To re-examine data on sperm counts over time from 61 studies from around the world. Design: Parametric analyses and flexible nonlinear models of the relation between sperm counts and time. Main Outcome Measure(s): Mean sperm concentrations per milliliter and regression coefficients for possible trends of concentrations over time. Result(s): A significant decline was found only in U.S. studies. Conclusion(s): Studies from specific sites have found declines in sperm counts, but a world-wide decline has not been demonstrated. Rigorous assessment of statistical models should be done before conclusions are drawn. Flexible smoothing models are a useful addition to currently available analytic methods.
KW - Mean sperm counts
KW - Meta-analysis
KW - Statistical modeling
UR - http://www.scopus.com/inward/record.url?scp=0030961755&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030961755&partnerID=8YFLogxK
U2 - 10.1016/S0015-0282(97)81446-X
DO - 10.1016/S0015-0282(97)81446-X
M3 - Article
C2 - 9176451
AN - SCOPUS:0030961755
VL - 67
SP - 1103
EP - 1108
JO - Fertility and Sterility
JF - Fertility and Sterility
SN - 0015-0282
IS - 6
ER -