STAT 301 Study Guide - Midterm Guide: Sampling Distribution, Mean Absolute Difference, Point Estimation

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lemondog142

27 Mar 2014

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Goal is to compare the mean of the variable for one population to the mean of the variable in the second. So our parameter of interest is 1 2. We can have two samples of different sizes, n1 and n2. Both n1 and n2 are greater than or equal to 30 (or both populations normal/combo) Sample 1 and sample 2 selected independently of each other. We want to make inferences about 1 2. X2 is the point estimate for 1 - 2. We need the sampling distribution of x1 and confidence intervals. X2 in order to construct hypothesis tests. If the random samples are independent of one another and n1 and n2 are both large ( . Most common hypotheses compare the difference to 0, but could also compare to some other number. Case 1: 1 and 2 both known, assumptions hold.

Related Questions

1. Matt, the manager, wants to estimate the mean wait time for customers to check out in his Mini-Market. He randomly selects customers and determines the mean wait time is minutes. Define the following for this exercise:

a) Is the data collected qualitative or quantitative?

b) Variable (x):

c) Population of Interest:

d) Sample:

e) Parameter of Interest and Statistic: Do you expect the parameter and the statistic to be the same value? Explain.

f) Discuss the use of descriptive and inferential statistics in this exercise.

g) Is the variable, x, discrete or continuous?

2. Identify the population and sample for the following examples:

The P.E. coach of a middle school interested in the mean height for the graders in the school. He randomly selects graders and measures the height of each.

a) Population:

b) 7thgraders Sample:

c) A community college notices that an increasing number of full-time students are working while attending school. The administration randomly selects 200 students and determines how many hours per week each student works.

fuchsiatermite35

1. Matt the Manager wants to estimate the mean wait time for customers to check out in his Mini-Market. He randomly selects 40 customers and determines the mean wait time is 2.7 minutes. Define the following for this exercise:Experimental Unit or Individual: Is the data collected qualitative or quantitative?Variable (x):Population of Interest:Sample:Parameter of Interest:Statistic:Do you expect the parameter and the statistic to be the same value? Explain.Discuss the use of descriptive and inferential statistics in this exercise.Is the variable, x, discrete or continuous?

2. Identify the populationand samplefor the following examples:a)The P.E. Coach of a middle school interested in the mean height for the 7thgraders in the school. He randomly selects 40 7thgraders and measures the height of each.Population: 7thgraders Sample: 40 7thgraders chosenb)A community college notices that an increasing number of full-time students are working while attending school. The administration randomly selects 200 students and determines how may hours per week each students works.

fuchsiatermite35

A salesperson makes four calls per year. A sample of 100 days given the following frequencies of sales volumes.

Number of Sales	Observed Frequency (days)
0	30
1	32
2	25
3	10
4	3
TOTAL	100

Records show sales are made to 30% of all sales calls. Assuming independent sales calls, the number of sales per day should follow a binomial distribution. The Binomial distribution is represented by:

For this exercise, assume that the population has a binomial probability distribution with n=4, p=0.30 and x= 0, 1, 2, 3 and 4.

(a) Compute the expected frequencies for x=0, 1, 2, 3 and 4 by using the binomial probability function. Combine categories if necessary to satisfy the requirement that the expected frequency is five or more for all categories.

(b) Use the goodness of fit test to determine whether the assumption of a binomial probability distribution should be rejected. Because no parameters of the Binomial probability distribution were estimated from the sample data, the degrees of freedom are k-1 .

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STAT 301 Study Guide - Midterm Guide: Sampling Distribution, Mean Absolute Difference, Point Estimation

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