# Is it alright to remove $\frac{N' - 1}{N'}$ from the formula of weighted standard deviation?

$$\sqrt{\frac{\sum_{i = 1}^N{w_i \left( x_i - \overline{x}_w \right)^2}}{\frac{\left( N' - 1 \right) \sum_{i = 1}^N {w_i}}{N'}}}$$

Is it acceptable to remove the $$\frac{N' - 1}{N'}$$ from the formula of weighted standard deviation?

Since $$\frac{N' - 1}{N'}$$ is approximately 1. If it is allowed, can you give me a reference. Thank you very much.

• What's $N'$ here means? – oszkar Apr 16 '20 at 9:54
• the N' prime is the number of weights that are not equal to zero – Ji Pa Apr 16 '20 at 9:59
• Are you sure it's the number of non-zero weights, not the sum of them? And why do you want to remove it? – oszkar Apr 16 '20 at 10:38