Methodology Report & Survey Data Essay Example | Topics and Well Written Essays - 1250 words

Methodology Report & Survey Data - Essay Example Assume that the distribution is normally distributed. 2.2 In order to estimate the percentage of dwellings which have a smoke alarm in the North West to within 1% for a 95% confidence level a pilot survey was carried out. From a random sample of 30 buildings, 12 were found to have a smoke alarm installed. How many houses need to be sampled in the main survey 2.3 Two counties were surveyed by a local council in an investigation of their effectiveness in reducing the number of buildings of multiple occupancy "at risk" from arson. The following data was obtained from the survey. Evaluation of data from each local council Total Number reducing Number remains the same Number increasing County A 6 25 38 69 County B 3 14 4 21 Total 9 39 42 90 Expected Values 6.9 29.9 32.21 2.1 9.1 9.8 O E (O-E) (O-E)2 (O-E)2/E 6 6.9 - 0.9 0.81 0.12 3 2.1 0.9 0.81 0.38 25 29.9 - 4.9 24.01 0.80 14 9.1 4.9 24.01 2.64 38 31.2 5.8 33.64 1.04 4 9.8 -5.8 33.64 3.43 Total 8.41 Significance = (-1)/(C-1) = (2-1)/(3-1) = 2 The calculated value of 8.41 is considerably more than the significance value of 2 Therefore the data represents a significant departure from the expected values thus County A shows a considerable increase in risk of arson as compared with County B and the trend is