Question
In an article in Accounting and Business Research, Carslaw and Kaplan investigate factors that influence "audit delay" for firms in New Zealand. Audit delay, which is defined to be length of time (in days) from a company's financial year-end to the date of the auditor's report, has been found to affect the market reaction to the report. This is because late reports often seem to be associated with lower returns and early reports often seem to be associated with higher returns. Carslaw and Kaplan investigated audit for two kind of public companies-owner controlled and manager controlled companies, Here a company is considered to be owner controlled if 30 percent or more of the common stock is controlled by a single outside investor (an investor not part of the management group or board of directions). Otherwise a company is considered manager controlled. It was felt that type of control influences audit delay. To quote Carslaw and Kaplan: Large external investors, having an acute need for timely Information, may be expected to pressure the company and auditor to start and to complete the audit as rapidly as practicable. (a) Suppose that a random sample of 108 public owner-controlled companies in New Zealand is found to give a mean audit delay of x = 82.10 days, and assume that sigma equals 30 days. Calculate a 95 percent confidence interval for the population mean audit delay for all public owner-controlled companies in New Zealand. (Round your answers to 3 decimal places.) The 95 percent confidence interval is [_____, ______]. (b) Suppose that a random sample of 108 public manager-controlled companies in New Zealand is found to give a mean audit delay of x = 96 days, and assume that a equals 33 days. Calculate a 95 percent confidence interval for the population mean audit delay for at public manager-controlled companies in New Zealand. (Round your answers to 3 decimal places.) The 95 percent confidence interval is [_____, ______] (c) Use the confidence Intervals you computed in pads a and b to compare the mean audit delay for all public owner-controlled companies versus that of all pubic manager-controlled companies. How do the means compare? Mean audit delay for public owner-controlled companies appears to be ______ and there is _______ amount of overlap of the intervals.
Explanation / Answer
a) here std error of mean =std deviation/(n)1/2 =2.887
for 95% confidence level ; z=1.96
therefore 95% confidence interval =sample mean -/+ z*std error=76.442 ; 87.758
b)
here from above data I am confused because of picture qualty if mean is 96 or 98. I am considering that as 96. please revert if it is not so.
here std error of mean =std deviation/(n)1/2 =3.175
for 95% confidence level ; z=1.96
therefore 95% confidence interval =sample mean -/+ z*std error=89.776 ; 102.224
c)mean audit...........apeears to be lower and there is nil amount of overlap of the intervals.
please revert for any clarification required.
