A market researcher wants to conduct a survey to estimate the population proportion who prefer Coca-Cola to Pepsi. Before conducting the survey, the researcher wants to choose a sample size so that the half width of the 99% confidence interval is no more than 2%, regardless what he will find. What is the required sample size?
Hints: recall that we only deal with "large n" population proportion questions in the class, so use the Z distribution. Also recall that the worst case for p-hat is when p-hat = 0.5.
Sample size = Z2/2 * ( 1 - ) / E2
= 2.57582 * 0.5 * 0.5 / 0.022
= 4146.7
n = 4147 (Rounded up to nearest integer)
A market researcher wants to conduct a survey to estimate the population proportion who prefer Coca-Cola...
A market researcher wants to conduct a survey to estimate the population proportion who prefer Coca-Cola to Pepsi. Before conducting the survey, the researcher wants to choose a sample size so that the half width of the 99% confidence interval is no more than 2%, regardless what he will find. What is the required sample size? Hints: recall that we only deal with "large n" population proportion questions in the class, so use the Z distribution. Also recall that the...
A researcher wants to estimate the proportion of a population which possesses a given characteristic. A random sample of size 200 is taken and 30% of the sample possesses the characteristic. The 90% confidence interval to estimate the population proportion is _______.
UTVU 4. If a researcher wants to estimate a population proportion to be within 4 percentage points with a 95% confidence if she uses the estimate from a recent study that showed its value to be 85%, what size sample should she obtain?
5. Let p be the proportion of the population who respond yes. a) In a survey of 700 US adults, 118 felt that alcoholism was a reasonable excuse for criminal conduct. Use the information to find p-hat & q-hat. b) Find the maximum error of estimate for p, with a 93% confidence level (assume normally distributed). c) Find the confidence interval with a 93% confidence level.
b.) A state-wide survey indicates that the proportion is 0.65. Using this estimate, what sample size is needed so that the confidence interval will have a margin of error of 0.07 2) A researcher wants to construct a 99% confidence interval for the proportion of elementary school students in Seward County who receive free or reduced-price school lunches.
A researcher wants to create a 90% confidence interval for the population proportion, with the margin of error of 3%. She has no idea what the population proportion is and she cannot take a trial sample. Calculate the required sample size.
A researcher wishes to estimate, with 99% confidence, the population proportion of adults who say chocolate is their favorite ice cream flavor. Her estimate must be accurate within two% of the population proportion. (a) No preliminary estimate is available. Find the minimum sample size needed. (b) Find the minimum sample size needed, using a prior study that found that 44% of the respondents said their favorite flavor of ice cream is chocolate. (c) Compare the results from parts (a) and...
A researcher wants to estimate the proportion of the population which possesses a given characteristic. A random sample of size 1800 is taken resulting in 450 items which possess the characteristic. The point estimate for this population proportion is _______.
5. Suppose a consumer advocacy group would like to conduct a survey to find the proportion p of consumers who bought the newest generation of an MP3 player were happy with their purchase. The advocacy group took a random sample of 1000 consumers who recently purchased this MP3 player and found that 400 were happy with their purchase. (a) Find a 95% lower bound for p (b) How large a sample size n should they take to estimate p with...
A researcher wishes to estimate with 99% confidence, the population proportion of adults who eat fast food four to six times per week.Her estimate must be accurate within 5% of the population proportion. a) no preliminary estimate is avaiable, find the minimum sample size needed. b) find the minimium sample size needed, using a prior study that found that 38% of the respondents said they eat fast food four to six times per week c) compare the results from parts...