Linking Image Quantitation and Data Analysis

Until recently, image-based experimentation in molecular biology has been primarily concerned with qualitative results produced as a result of such experiments as Northern blots, immunoblotting, and gel electrophoresis. These experiments result in a relatively small number of bands on an autorad or other imaging medium. These bands or spots would be visually inspected to determine their “presence” or “absence,” or visually compared with other spots on the medium to determine their relative intensities. Sometimes, comparisons would be enhanced using quantities derived from densitometry analysis. Such comparisons were often performed to provide a numerical summary of a clearly visible difference. This summary may have been required for publication of the experimental results. This approach seemed to serve the investigator well because there existed no real need for accurate image quantitation or data analysis and a simple qualitative result would suffice.