# Can you help?

#### arhodes1

##### New Member
Can anyone help with survey sampling?

I need help with my Sampling Methods class. I have three homework questions that I have no idea how to solve...If anyone who knows survey sampling please help!! thanks! Amanda

#### quark

##### Admin
Welcome arhodes, if you post the questions here I'll see if I can help.

#### arhodes1

##### New Member
Here are the problems.

1. List all possible simple random samples of size n=2 that can be selevted from the population (0,1,2,3,4,). Calculate o^2 for the population and V(y with a bar over the y) for the sample.

2. For the simple random samples generaed in the previous question calculate s^2 for each sample. Show numerically that

E(s^2)=(N/(N-1))o^2

3. A simple random sample of 100 water metes within a community is monitored to estimate the average daily water consumption per houseold over a specified dry spell. The sample mean and sample variance are found to be mean 12.5 and sd 1252. Estimate the total number of gallons of water, t, used daily during the dry spell. Place a boud on the error of estimation.

Hopefully you can help me! thanks. Amanda

#### quark

##### Admin
For #1, you can list all possible pairs (0,1), (0,2)...(3,4). I assume sampling without replacement. sigma^2 for the population can be calculated using the formula for std. dev. For variance of ybar, you calculate the eman from each ample, then apply the formula for sd.

For #2 you follow the definition of s^2 and sigma^2. It should be straightforward.

#3 seems to be a confidence interval problem.

#### arhodes1

##### New Member
how do you calculate the mean for each sample? and how do you do a confidence interval problem?

#### quark

##### Admin
For (0,1), the mean is 0.5, for (0,2) the mean is 1...

There should be a few examples of calculating confidence interval in your textbook or lecture notes.

#### pla0812

##### New Member
I have attached an excel spreadsheet that may assist you with your confidence intervals and sample.

#### quark

##### Admin
Hi pla,

This is a nice little program. Do you have a spreadsheet for regression? Thanks.

#### pla0812

##### New Member
Sorry, I don't have one for regression yet.