Statistical Bulletin Transport Series Scottish Household Survey: Travel Diary 2009/2010

Table 30: [Confidence limits] 95% confidence limits for estimates, based on SHS sub-samples sizes
Sub-sample size (=100%) Estimate
5% 10% 15% 20% 25% 30% 35% 40% 45%
or or or or or or or or or
95% 90% 85% 80% 75% 70% 65% 60% 55% 50%
    percentage points  ( + / - )
100 5.1 7.1 8.4 9.4 10.2 10.8 11.2 11.5 11.7 11.8
200 3.6 5.0 5.9 6.7 7.2 7.6 7.9 8.1 8.3 8.3
300 3.0 4.1 4.8 5.4 5.9 6.2 6.5 6.7 6.8 6.8
400 2.6 3.5 4.2 4.7 5.1 5.4 5.6 5.8 5.9 5.9
500 2.3 3.2 3.8 4.2 4.6 4.8 5.0 5.2 5.2 5.3
600 2.1 2.9 3.4 3.8 4.2 4.4 4.6 4.7 4.8 4.8
700 1.9 2.7 3.2 3.6 3.8 4.1 4.2 4.4 4.4 4.4
800 1.8 2.5 3.0 3.3 3.6 3.8 4.0 4.1 4.1 4.2
900 1.7 2.4 2.8 3.1 3.4 3.6 3.7 3.8 3.9 3.9
1,000 1.6 2.2 2.7 3.0 3.2 3.4 3.5 3.6 3.7 3.7
1,200 1.5 2.0 2.4 2.7 2.9 3.1 3.2 3.3 3.4 3.4
1,400 1.4 1.9 2.2 2.5 2.7 2.9 3.0 3.1 3.1 3.1
1,600 1.3 1.8 2.1 2.4 2.5 2.7 2.8 2.9 2.9 2.9
1,800 1.2 1.7 2.0 2.2 2.4 2.5 2.6 2.7 2.8 2.8
2,000 1.1 1.6 1.9 2.1 2.3 2.4 2.5 2.6 2.6 2.6
2,500 1.0 1.4 1.7 1.9 2.0 2.2 2.2 2.3 2.3 2.4
3,000 0.9 1.3 1.5 1.7 1.9 2.0 2.0 2.1 2.1 2.1
3,500 0.9 1.2 1.4 1.6 1.7 1.8 1.9 1.9 2.0 2.0
4,000 0.8 1.1 1.3 1.5 1.6 1.7 1.8 1.8 1.9 1.9
5,000 0.7 1.0 1.2 1.3 1.4 1.5 1.6 1.6 1.7 1.7
6,000 0.7 0.9 1.1 1.2 1.3 1.4 1.4 1.5 1.5 1.5
7,000 0.6 0.8 1.0 1.1 1.2 1.3 1.3 1.4 1.4 1.4
8,000 0.6 0.8 0.9 1.1 1.1 1.2 1.3 1.3 1.3 1.3
9,000 0.5 0.7 0.9 1.0 1.1 1.1 1.2 1.2 1.2 1.2
10,000 0.5 0.7 0.8 0.9 1.0 1.1 1.1 1.2 1.2 1.2
12,000 0.5 0.6 0.8 0.9 0.9 1.0 1.0 1.1 1.1 1.1
14,000 0.4 0.6 0.7 0.8 0.9 0.9 0.9 1.0 1.0 1.0
16,000 0.4 0.6 0.7 0.7 0.8 0.9 0.9 0.9 0.9 0.9
18,000 0.4 0.5 0.6 0.7 0.8 0.8 0.8 0.9 0.9 0.9
20,000 0.4 0.5 0.6 0.7 0.7 0.8 0.8 0.8 0.8 0.8
25,000 0.3 0.4 0.5 0.6 0.6 0.7 0.7 0.7 0.7 0.7
30,000 0.3 0.4 0.5 0.5 0.6 0.6 0.6 0.7 0.7 0.7
35,000 0.3 0.4 0.4 0.5 0.5 0.6 0.6 0.6 0.6 0.6
40,000 0.3 0.4 0.4 0.5 0.5 0.5 0.6 0.6 0.6 0.6
45,000 0.2 0.3 0.4 0.4 0.5 0.5 0.5 0.5 0.6 0.6
50,000 0.2 0.3 0.4 0.4 0.5 0.5 0.5 0.5 0.5 0.5

e.g. an estimate of 55% that is based on a sample of 800 has 95% confidence limits of 55% ± 4.1% points