

Once you have set a threshold significance level (usually 0.05), every result leads to a conclusion of either "statistically significant" or not "statistically significant". Some statisticians feel very strongly that the only acceptable conclusion is significant or 'not significant', and oppose use of adjectives or asterisks to describe values levels of statistical significance.
Many scientists are not so rigid, and so prefer to use adjectives such as “very significant” or “extremely significant”. Prism uses this approach as shown in the tables below. These definitions are not entirely standard. If you report the results in this way, you should define the symbols in your figure legend.
Older versions of Prism use the scheme below. So does Prism 7 if you choose GP formatting or if you ask for four or more digits after the decimal point.
P value 
Wording 
Summary 
< 0.0001 
Extremely significant 
**** 
0.0001 to 0.001 
Extremely significant 
*** 
0.001 to 0.01 
Very significant 
** 
0.01 to 0.05 
Significant 
* 
≥ 0.05 
Not significant 
ns 
If you choose APA or NEJM formatting for P values, Prism uses this scheme (note the absence of ****).
P value 
Wording 
Summary 
< 0.001 
Very significant 
*** 
0.001 to 0.01 
Very significant 
** 
0.01 to 0.05 
Significant 
* 
≥ 0.05 
Not significant 
ns 
Prism stores the P values in double precision (about 12 digits of precision), and uses that value (not the value you see displayed) when it decides how many asterisks to show. So if the P value equals 0.05000001, Prism will display "0.0500" and label that comparison as "ns".