In observational studies, investigators usually do not have the same control over the treatment assignment as they do with randomized controlled studies. As a result, the treatment and control groups may have a large difference on their observed covariates. These differences could lead to bias in estimating treatment effects. There are several propensity score based methods that could reduce th...

Background & Aims: The purpose of the present research was to compare the bone mineral density (BMD) of lumbar spine between athletic and non-athletic premenopausal women. Methods: Fifteen female athletes (runner) with the mean age of 33.80 ± 4.81 years, mean height of 164.13 ± 5.31 cm, mean weight of 57.33 ± 4.22 kg, and mean body mass index (BMI) of 21.41 ± 2.21 kg/m2 and 15 female non-athlet...