Sampling

A company is trying to see if it it’s customers would prefer to expand their clothing section or their home store section. Since they are a national company, performing a census is unrealistic and therefore they will survey a sample.

Randomly select one store and ask 30 of the customers at this store their opinion A. Simple Random Sample B. Stratified Random Sample C. Systematic Sampling D. Cluster Sampling

Put an advertisement in the newspaper asking people to mail in their vote A. Simple Random Sample B. Voluntary Response Sample C. Convenience Sample D. Stratified Random Sample

Send a survey to every customer’s home and ask the customer to fill it out and return it A. Simple Random Sample B. Voluntary Response Sample C. Convenience Sample D. Stratified Random Sample

Go through the company’s records, selecting every 100 th customer. Survey every person chosen. A. Simple Random Sample B. Stratified Random Sample C. Systematic Sampling D. Cluster Sampling

Randomly select 20 customers from each store. Send each a survey and follow up with a phone call if they do not return the survey within a week A. Simple Random Sample B. Stratified Random Sample C. Systematic Sampling D. Cluster Sampling

Sponsor a commercial during a TV program and ask people to call in their preferences. A. Simple Random Sample B. Voluntary Response Sample C. Convenience Sample D. Stratified Random Sample

Go through the company’s records, and select a random 100 customers. Survey every person chosen. A. Simple Random Sample B. Stratified Random Sample C. Systematic Sampling D. Cluster Sampling

Central Limit Theorem

CLT O In a non-normal distribution, the sample means will fall normally around the population mean. (If, the sample means are obtained from random samples with size 30 or larger.) O 2 conditions: O Large Sample Size (n>30) O Simple Random Sample

The life expectancy in America is non - normal with an average of 72years and a standard deviation of 15 years. O What is the probability that a randomly selected American will live to be 80 years old. O What is the probability that you will have obtain a random sample of 45 people with a sample mean of 98 years.

Confidence Intervals

A box of Lucky Charms promises an average 15 oz of cereal per box. You want to test this claim, so you tested a sample of 40 boxes. The average amount of cereal in these 40 boxes was 13 oz with an estimated s = 8.8oz. O Create a 95% confidence interval for your estimated average. O Do you think the company is holding up to their promise?

Which sentences properly Interpret this confidence interval??? O I am 95% confident the average body temperature of an American is between 96.9 and 99.3 degrees. O 95% of Americans have a body temperature between 96.9 and 99.3 degrees O The average body temperature of an American is between 96.9 and 99.3 degrees. O 95% of samples have an average between 96.9 and 99.3 O 95% of confidence intervals from the samples I take will contain the true average American body temperature. In trying to predict average body temperature of Americans, I got a 95% confidence interval of… ( )

Interpretation O I am 95% that ______(your parameter)____ is between ______ and ______

Hypothesis Testing

The 2 options when dealing with null and alternative hypotheses When do you choose this option? Interpretation Sentence

The average college student pays $20,335 per year in tuition. In order to see if Iowa State costs are less than the national average, a random sample of 100 ISU students is taken.

O When you run a hypothesis test you obtain the following output… The average college student pays $20,335 per year in tuition. In order to see if Iowa State costs are less than the national average, a random sample of 100 ISU students is taken. Your sample of 100 students pays an average of $18,856 and has a sample standard deviation of $8,750. What can you conclude about ISU tuition costs?

Putting it all together

The situation You are DISH Network. You are trying to decide whether to offer a new sports channel. You are willing to offer it if it seems to have a customer ranking of at least 7.5 (out of 10).

Basics  You are DISH Network. You are trying to decide whether to offer a new sports channel. You are willing to offer it if it seems to have a customer ranking of at least 7.5 (out of 10). What is the population? What is your parameter?

O You decide to take a sample of 125 of your customers. O What type of sample should you take? O Can you still make assumptions even if the population distribution is non-normal?  You are DISH Network. You are trying to decide whether to offer a new sports channel. You are willing to offer it if it seems to have a customer ranking of at least 7.5 (out of 10).

Null and Alternative Hypothesis What is your Null hypothesis and alternative hypothesis?  You are DISH Network. You are trying to decide whether to offer a new sports channel. You are willing to offer it if it seems to have a customer ranking of at least 7.5 (out of 10).

Confidence interval Your sample yields an average of a 6.8 rating. Your sample standard deviation is Create a 95% confidence interval for the population parameter.  You are DISH Network. You are trying to decide whether to offer a new sports channel. You are willing to offer it if it seems to have a customer ranking of at least 7.5 (out of 10). You take a 125-customer random sample

Hypothesis Test  You are DISH Network. You are trying to decide whether to offer a new sports channel. You are willing to offer it if it seems to have a customer ranking of at least 7.5 (out of 10). You take a 125-customer random sample

Conclusion O Are you going to offer this new sports channel? O Using confidence interval O Using your hypothesis test