## Comparison of Means |
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## Assigned Reading- Comparison of means Read►
## PresentationsThere are three sets of presentations for this lecture: - Normal distribution Slides► Video► YouTube►
- Use Excel function for Z test YouTube►
- Introduction to Control Chart Slides► Listen►
- X-bar chart lecture Slides► Listen►
- XmR chart Slides► Listen►
- Risk Adjusted X-bar chart lecture Slides► Listen►
- Use Excel to create X-bar chart Excel 2003► Video► SWF►
- Use Excel to create risk adjusted X-bar chart Excel 2003►
- Dot plots and the mean Video►
- Histograms and shape How to► How to► Video►
- Two sample Z test Video►
- Calculating Z scores Video► Online Calculator►
Narrated slides and videos require Flash. ## Assignments
In these files the denominator indicates the number of patients. Payment indicates average payment per patient. Select data for hospitals that had at least 100 patients. Submit an Excel file containing the control chart for the data. Download►
Note that the field HBIPS-2_Overall_Num indicates the numerator for the measure "Hours of physical-restraint use." The denominator for the same overall measure is in the field HBIPS-2_Overall_Den. The dictionary provides the interpretation of these two fields as hours of restraint and number of patients examined. Using the procedure for XmR control chart examine if the total number of hours of restraints has changed over time. Download► Dictionary►
(a) Compute descriptive statistics for each variable. Answer► Donthula's Teach One► (b) Use Excel to perform a one sample test to evaluate whether or not the mean motivation level of all employees in the population is different from 5. The null hypothesis is that µ1 = 5; i.e. the population mean motivation level is equal to 5. The alternative hypothesis is that µ1 ≠ 5; i.e. the population mean motivation level is significantly different from 5. Calculate the mean (4.31) and the standard deviation (3.00) using functions in Excel. Calculate the t-statistic and its degrees of freedom. Calculate the critical value and test if the critical value is less than alpha of 0.05. Copy/paste relevant Excel output. Provide interpretation of "t" test results. Donthula's Teach One► (c) Use Excel to perform a paired samples t-test to evaluate whether or not the mean Motivation level is significantly different from mean Commitment level in the population. The null hypothesis is that µ1 = µ2, i.e. the sample mean motivation level is equal to the sample mean commitment level. The alternative hypothesis is that µ1 ≠ µ2, i.e. the sample mean motivation level is significantly different from the sample mean commitment level. Test at alpha levels less than 0.05. Copy/paste relevant Excel output. Provide interpretation of t-test results. Answer► Chintalapani's Teach One► (d) Use Excel to perform an independent samples t-test (assuming equal variances) to evaluate whether or not the mean Motivation level differs significantly between male and female employees in the population. The null hypothesis is that µ1 = µ2; i.e. the sample mean motivation level for females is equal to the sample mean motivational level for males. The alternative hypothesis is that µ1 ≠ µ2; i.e. the sample mean motivation level for females is significantly different from the sample mean motivational level for males. Copy/paste relevant Excel output. Provide interpretation of t-test results. For this problem you can assume that a pooled variance test is appropriate and alpha level is 0.05. Answer► Chintalapani's Teach One► (e) Compare the performance of Medstar Washington to other DC based hospitals on several measures available in Hospital Compare. What advice you have for the hospital administrator on where improvements are needed. Answer► ## More- Information on calculation of standard deviations Google►
- Annotated bibliography of using control charts to improve health care. PubMed►
- Student-t distribution More►
- Badii's lecture on normal distributions Part
1► Part
2►Slides►
**SPSS tutorial►** - Measures of central tendency Video►
**SPSS tutorial►**
This page is part of the course on Statistical Process Improvement, the lecture on Comparison of Means. This course was created by Farrokh Alemi, Ph.D. on January 22, 2016 |