Complex sentence: For example, with the transit method, one of the more successful, measurement of radius can be highly accurate, but mass and density are often estimated; likewise with radial velocity methods, which provide accurate measurements of mass but are less successful measuring radius.
Split into simpler sentences: For example, with the transit method, one of the more successful methods, measurement of radius can be highly accurate, however mass and density is often estimated. Likewise with radial velocity methods, which provide accurate measurements of mass but are less successful measuring radius.