Slovin's Formula is a Statistical Formula used to determine the sample size needed for a population with a certain level of precision

1. Slovin's Formula
Annjon L. Saracia

2. What is Slovin's
Formula?
-invented by Robert Slovin and it is used
to calculate the sample size (n) given
the popultaion size (N) and a margin of
error (e)r
• it is a random sampling technique
formula to estimate sampling size
n= N/(1+Ne2)

3. When to use Slovin's Formula?
If a sample taken from a population, a formula must be used to take into account
confidence levels and margins of error. When taking statistical samples, sometimes
a lot is known about a population, sometimes a little and somethings nothing at all.

4. How to use Slovin's Formula?
To use the formula, first figure out what you want your error of toelrance to be. For
example, you may happy with a confidence level of 95% (giving of margin of error of
0.05), or you may require a tighter accuracy of a 98% confidence level ( a margin of
error of 0.02). Plug your population size and required margin of error into the formula.
The result will be number of samples you need to take.

5. Example
Supposed that you have a group of 1,000 city government employees and you want to
survey them to find out which tools are best suited to their jobs. You decide that you are
happy with a margin of error of 0.05. Using Slovin's Formula, you would be required to
survey n=N/1+Ne2)
n= 1000/ (1+1000*0.05*0.05)
n= 1000/ (1+1000* 0.0025)
n=1000/ (1+ 2.5)
n=1000/3.5
n= 285.714
n=286

6. Example
A researcher plans to conduct a survey. If the population on La Carlota City
is 10,000, find the sample size if the margin of error is 25%
n= 10,000/(1+10,000*0.025*0.025)
n=10,000/( 1+10,000*0.000625)
n=10,000/( 1+6.25)
n=10,000/7.25
n=1,379.310
n=1,380