Table 1 Factors that affect sample size calculations
| Factor | Magnitude | Impact on identification of effect | Required sample size |
|---|---|---|---|
| P value | Small | Stringent criterion; difficult to achieve 'significance' | Large |
| Large | Relaxed criterion; 'significance' easier to attain | Small | |
| Power | Low | Identification unlikely | Small |
| High | Identification more probable | Large | |
| Effect | Small | Difficult to identify | Large |
| Large | Easy to identify | Small |