USEFUL STUFF – SAMPLE DATA DEVIATION TABLE
Sample deviation (confidence interval) depends on 3 factors:
 Sample size
 Confidence level
 Parameter value in sample
Confidence intervals decrease (sample deviation decreases) when…
 Sample size is increased
 Confidence level is decreased
 When the parameter value is close to 0% or 100% (confidence interval is biggest at 50%)
95% confidence level is the most widely accepted standard for evaluating study data deviation.
Sample size 
Confidence level 95% 
Parameter value, % 

5.0 
10.0 
20.0 
30.0 
40.0 
50.0 
60.0 
70.0 
80.0 
90.0 
95.0 

50 
Low 
0.8 
3.3 
10.0 
17.9 
26.4 
35.5 
45.2 
55.4 
66.3 
78.2 
84.8 
High 
15.2 
21.8 
33.7 
44.6 
54.8 
64.5 
73.6 
82.1 
90.0 
96.7 
99.2 

100 
Low 
1.6 
4.9 
12.7 
21.2 
30.3 
39.8 
49.7 
60.0 
70.8 
82.4 
88.7 
High 
11.3 
17.6 
29.2 
40.0 
50.3 
60.2 
69.7 
78.8 
87.3 
95.1 
98.4 

200 
Low 
2.4 
6.2 
14.7 
23.7 
33.2 
42.9 
52.9 
63.1 
73.8 
85.0 
91.0 
High 
9.0 
15.0 
26.2 
36.9 
47.1 
57.1 
66.8 
76.3 
85.3 
93.8 
97.6 

300 
Low 
2.8 
6.8 
15.6 
24.9 
34.4 
44.2 
54.2 
64.5 
75.0 
86.0 
91.9 
High 
8.1 
14.0 
25.0 
35.5 
45.8 
55.8 
65.6 
75.1 
84.4 
93.2 
97.2 

500 
Low 
3.3 
7.5 
16.6 
26.0 
35.7 
45.5 
55.6 
65.8 
76.2 
87.0 
92.7 
High 
7.3 
13.0 
23.8 
34.2 
44.4 
54.5 
64.3 
74.0 
83.4 
92.5 
96.7 

1000 
Low 
3.7 
8.2 
17.6 
27.2 
36.9 
46.9 
56.9 
67.1 
77.4 
88.0 
93.5 
High 
6.5 
12.0 
22.6 
32.9 
43.1 
53.1 
63.1 
72.8 
82.4 
91.8 
96.3 
EXAMPLE:
It can be stated with 95% confidence that, at a sample size of 1000 and an observed value of 20%, the value of the parameter in the parent population will be in the interval of 17.6% to 22.6%.
To calculate sample error for parameter values not in the table, you can use the following calculator: