Lecture 10:

For this set of problems use the file named Homes.xlsx. SuperMaxx now wishesto gain insight into the prices for homes sold in the given area generally. In particular they wish to know how style and having a pool affect selling price. They are also interested in understanding if the quality of view generally influences the style of home built on a lot.

For the next few problems, use, create a derived variable STYLE-POOL and use it to unstack PRICE. You should end up with 5 groups of prices for style and pool combinations.

1. Obtain 95% confidence intervals for the population mean price for all combinations of STYLE and with/without a pool. Also check whether it's ok to assume the data is normal by getting skewness and kurtosis values. Confirm your conclusion by inspecting the box plot or NPP. What can you conclude about the accuracy of the confidence interval estimate? Write a one sentence interpretation of the 95% confidence estimate of the population mean price for homes of a given Style with and without a pool. Do not discuss groups with less than 4 samples since few meaningful statistics are possible with such a small sample.

PHStat does not have a convienet way to compute the CI's for multiple groups at once so use Analysis Toolpak - Descriptive statistics which can make a table for all the combinations at once, or the t-CI tab on the Parametric_CI_HypTest.xlsx or manually compute using confidence.t(). It is suggested you make a table summarizing your results:

SAD1Pool SAD2Pool SAD31 count 32 29 confidence interval 95.% lower 282.7961 269.7739 268.6 confidence interval 95.% upper 349.9481 337.7177 316.5 half-width 33.5760 33.9719 23.9 skewness 1.0783 1.4422 1.5 kurtosis 0.3923 1.7533 3.5 coefficient of variation (CV) 29.44% 29.40% 21 Normal assumption? Not normal Not Normal Large sample? n > 30 small n 12 results accurate? OK Not OK*Data Analysis Analysis Tools OK Descriptive Statistics Cancel Exponential Smoothing F-Test Two-Sample for Variances Fourier Analysis Histogram Moving Average Random Number Generation Dank and DareantilaDescriptive Statistics Input OK Input Range: SA$1:$0$28 Cancel Grouped By: Columns O Rows Labels in first row Output options O Output Range: New Worksheet Ply: New Workbook Summary statistics 95 % Confidence Level for Mean: O Kth Largest: OKth Smallest:Estimate for the Proportion Data Sample Size: 108 Number of Successes: 44) Confidence Level: 95 Output Options Title: Finite Population Correction Population Size: Help OK Cancel