Confused by * or ** on graphs? Our guide explains the meaning of asterisks (stars) for statistical significance and how programs like Prism use them to represent p-values.
When research data is shared in journals, graphs, or reports, you may notice **symbols such as *, , or *** next to values. These are called significance symbols or p value stars. They give a quick idea of how strong the result is, without needing to read the full number.
What Do P Value Stars Mean?
In statistics, the p value symbol tells us how likely a result happened by chance.
- A single asterisk (*) means the result is statistically significant at the 0.05 level.
- Two or more stars (** or ***) show stronger significance, meaning the chance of error is smaller.
These significance stars are widely used in software like Biostat prime, GraphPad Prism, InStat, and OriginPro, as well as in published research papers.
Table: P Value Significance Symbols
| Symbol | P Value | Meaning |
|---|---|---|
| ns | P > 0.05 | Not significant |
| * | P ≤ 0.05 | Statistically significant |
| ** | P ≤ 0.01 | Strong significance |
| *** | P ≤ 0.001 | Very strong significance |
| **** | P ≤ 0.0001 | Extremely strong significance |
Why Use Asterisks for P Values?
Writing the exact p value (like p = 0.032) is correct but can be harder to follow in a graph or table. Using p value asterisks makes it simple:
- A quick glance at the number of stars shows the level of importance.
- It keeps figures clear, especially in reports with many comparisons.
Software Styles for Significance Symbols
Different platforms show p value stars slightly differently:
- APA style: up to three stars (***) only.
- NEJM style: also three stars maximum.
- Biostst prime style: uses up to four stars (****) for very small p values.
- Older versions of Prism or InStat: usually showed only one asterisk if the test was significant.
This is why it’s always best to explain your star scale in the figure legend or methods section.
What Do the Asterisks Mean on a Graph? (*, **, ***)
When you read a scientific paper or look at a graph from an experiment, you often see asterisks (stars) next to bars or data points. These asterisks are a simple code for statistical significance. They tell you how confident the researchers are that their results are real and not just due to random chance.
This guide explains the common meaning of these symbols, focusing on how popular software like biostat uses them.
The Standard Code for Significance Stars
Most of the time, the asterisks follow a standard pattern. This table shows the most common meaning:
| Symbol | Meaning | P-Value Meaning |
|---|---|---|
ns | Not significant | P > 0.05 (Greater than 0.05) |
| * | Significant | P ≤ 0.05 (Less than or equal to 0.05) |
| ** | Very significant | P ≤ 0.01 (Less than or equal to 0.01) |
| *** | Highly significant | P ≤ 0.001 (Less than or equal to 0.001) |
| **** | Extremely significant (See note) | P ≤ 0.0001 (Less than or equal to 0.0001) |
Note on Four Asterisks (****): The use of four stars is not always standard. Some publications and software styles only use up to three stars (***) for any p-value less than 0.001.
What do *, , and *** mean in statistics?
They are significance symbols that represent p value levels. * means p ≤ 0.05, ** means p ≤ 0.01, and *** means p ≤ 0.001.
How many asterisks are used for significance?
It depends on the p-value. One asterisk () is for P ≤ 0.05. Two () is for P ≤ 0.01. Three () is for P ≤ 0.001. Many programs now use four (****) for P ≤ 0.0001.
What is the symbol for significance in graphs?
The p value star (asterisk) is the most common symbol. It helps readers understand results at a glance.
Should I report stars or actual p values?
Both are useful. Stars are quick to read, but the exact p value gives more detail. Many journals suggest including both.
What does “ns” mean in reports?
“ns” stands for not significant, meaning the result has p > 0.05 and is likely due to chance.
Is the cutoff less than (<) or less than or equal to (≤) 0.05?
Proper statistical software uses less than or equal to (≤). This means a p-value of exactly 0.05 is considered significant and gets one asterisk (*).
The meaning of the symbols can have slight variations. The graph or table should always include a key that defines what ns, *, **, and *** represent in that specific figure.