1.Could you please advice me how can I calculate capability of process with one sided specification? There is Lower specification limit and no upper specification limit. Suppose Cp can not be calculated. 2. Regarding collecting data for SPC from the specific process, I have another question. What is the best sampling frequency for collecting data for conducting SPC. Generally we apply rule: 5 pieces per each hour of manufacturing, overall 25 hours = 125 pcs. Is it a must, or other rules can be applied, for example 1 piece per shift. What is the minimum sample size?