Bottleneck station is defined as a point in the manufacturing process that holds down the amount of product which a factory can produce. It causes the inability of a system to respond to sudden changes in demand as a result of capacity restrictions. The study focuses on unbalanced lines in which one station, so called the bottleneck, has either a mean processing time or a variance larger than all other stations. By providing storage buffers, it has shown that line blocking and starving may be solved. However, the optimal placement of a predetermined amount of buffer capacity in different types of bottleneck condition is not well understood. Thus, this paper studies the relationship of bottleneck and buffer factors. These are factors that show characteristics of bottleneck condition and buffer type (e.g., size and position). Various statistical analyses are then used to find any significance or insignificance of performance measures under each situation. Results from the experiment have revealed some interesting knowledge in allocating storage buffers for productivity improvement.