Few guidelines promoting good health in children are available. Investigations into the development of standing and walking in infants who used babywalkers (wheeled seats that allow infants to move around with their feet on the floor) obtained conflicting results. Crouchman (64 infants) and Siegel and Burton (109 infants) found that the use of babywalkers was associated with delay in crawling. ...

The cross-sectional study design is sometimes avoided by researchers or considered an undesired methodology. Possible reasons include incomplete understanding of the research design, fear of bias, and uncertainty about the measure of association. Using causal diagrams and certain premises, we compared a hypothetical cross-sectional study of the effect of a fertility drug on pregnancy with a hyp...