# Statistics for the Healthcare Quality Professional

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Statistics for the Healthcare Quality Professional
Susan Mellott PhD, RN, CPHQ, FNAHQ Mellott & Associates LLC

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Objectives Use basic statistical techniques to describe data and to evaluate data Use or coordinate the use of statistical process control components Use or Coordinate the use of process analysis tools to display data Mellott & Associates LLC

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Mom Baseball Statistics Apple Pie Mellott & Associates LLC

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What Type of Data? The type of data that you have controls what tools, statistics and display format are utilized Everything is driven from this Mellott & Associates LLC

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Type of Data Measured Data Time, Volume, Money, Scores Run Chart Control Chart Mean, Median, Mode, Range T-test Category – Count Data Categories or groups Histogram Percentage Chi Squared Mellott & Associates LLC

Categorical Data Examples
Men vs Women Age Ranges (0-30, 31-50, 51-70, 71+) DRGs Types of falls Types of injuries Diagnosis Complications Mellott & Associates LLC

Measured Data Examples
Temperature LOS Average daily census Scores on a test Pre and Post Test scores Anything over time Mellott & Associates LLC

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In Healthcare Quality Use more measured data than categorical data, but there is a place for each Use more Run and Control charts than Histograms Mellott & Associates LLC

And then there are other Problem Solving Tools
Cause & effect diagram Pareto diagram Scatter diagram Regression analysis Mellott & Associates LLC

But First…… Some Basics
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Reliability and Validity
The ability to get the same answer time and time again if nothing changes Validity To be sure you are counting or measuring what you intended to count or measure Mellott & Associates LLC

Reliability and Validity
Must have reliability before you can have validity HINT: R comes before V in the alphabet Mellott & Associates LLC

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Reliability Test / Retest reliability Inter-Rater reliability *** Mellott & Associates LLC

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Validity Face Validity Lowest level Criterion Validity *** Based on criteria Construct Validity Hardest to obtain Mellott & Associates LLC

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Sampling How you pick your sample influences what you can do with your results Can you generalize the findings outside of the sample you used Are you confined to use your findings only in relation to the sample itself Probability vs Non-Probability Usually use of combination of each type Mellott & Associates LLC

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Probability Sampling You probably will be able to generalize your findings Simple Random All items have an equal chance of being chosen Stratified Random Creating 2 or more homogeneous groups and then randomly selecting items Men vs Women Systemic Random Every n’th case Mellott & Associates LLC

Non-Probability Sampling
You probably will not be able to generalize your findings Convenience Using data readily available Quota Set number of data sets Purposive Demonstrate a desired characteristic Expert sampling Men vs Women Mellott & Associates LLC

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Data Collection Must assure that measuring what you intend to measure Pre-test your data collection tool! Verify collection questions with requestor of the data Must assure that all data collectors collect the data from the same places and in the same manner Mellott & Associates LLC

Before Collect Data, Must:
Know how you want to manipulate data; Know how you want to display data; Know how you want to report data; All of which is based on type of data! Mellott & Associates LLC

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Categorical Data AKA: Attribute, Qualitative, Nominal, Ordinal, Discrete Examples: # of members, patients, births, procedures, occurrences, gender, ethnicity Mellott & Associates LLC

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Categorical Data Usually Reported as: % in each category, whole numbers Usually Displayed as: Histogram, pie chart Usual statistical test of difference between groups: Chi Squared Mellott & Associates LLC

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Measured Data AKA: Continuous, Variable, Quantitative Examples: Age, height, weight, temperature, time, charges, LOS Mellott & Associates LLC

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Measured Data Usually Reported as: Mean, median, mode, minimum, maximum, percentiles, whole and fractional numbers Usually displayed as: Run charts, control charts Usual statistical test of difference between groups: T-test, or in special cases a Z-test Mellott & Associates LLC

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Mean, Median, Mode Mean: Average Can be influenced by outliers/extreme values Median: Middle of data Best utilized when there are outliers Mode: Most frequently occurring numbers Mellott & Associates LLC

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Examples 2, 4, 6, 8, 10 Mean: Median: 2, 4, 6, 8, 100 Mellott & Associates LLC

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Example 2, 4, 6, 7, 8, 10 Mean: Median: 0, 0, 0, 0, 0, 7, 12, 26 Mellott & Associates LLC

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Examples 2, 4, 6, 8, 10 Mode: 2, 3, 3, 4, 6, 8, 10 2, 3, 3, 4, 4, 4, 6, 8, 10 Mellott & Associates LLC

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STANDARD DEVIATION Mellott & Associates LLC

Statistical Differences between Groups
Clinical differences occur before statistical differences Categorical data – Chi Square Measured data – T-test Mellott & Associates LLC

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Chi-Squared test Similar to a t-test Get an X2 value Then look that value up on a p-value table like a t-test score Mellott & Associates LLC

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T-test Reported as a ‘p’ score Ranges from 0 to 1 0.05 and less shows statistical differences 1 0.25 0.5 0.05 Mellott & Associates LLC

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Histogram (Bar Chart) What is it: A display of comparisons between different categories or groups When used: To look at differences between categories or groups (non-statistical differences) What it will tell you: What the amount of differences look like Mellott & Associates LLC

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Histogram vs Run Chart vs Control Chart
only with categorical data Best to display one to three points in time If more than three points in time, better to use run chart Much more effective than a pie chart Mellott & Associates LLC

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Run Chart (Line Graph) What is it: A line graph display of performance changes over time When used: To look at data over time What it will tell you: What is baseline performance? Amount and type of variation in a process? Is process changing over time? Is change an improvement? Mellott & Associates LLC

Histogram vs Run Chart vs Control Chart
Categorical data over time Sequential Data points Display comparison between years, hospital units, stratification of data Prior to having enough data for Control Chart Mellott & Associates LLC

Control Chart (Line Graph)
What is it: A line graph display that compares actual performance to the mean and includes upper and lower control limits When used: To display normal variations and out-of-control variations What it will tell you: Common cause or special cause variation Mellott & Associates LLC

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Control Chart Conceptually – Run chart with standard deviation curve placed on its side Mellott & Associates LLC

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Control Charts Mellott & Associates LLC

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Regression Analysis Simple Regression How one variable affects another variable Example: number of calories eaten vs weight gain Multiple Regression How multiple variables affect another variable Factors related to compliance with medication regime Mellott & Associates LLC

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Regression Analysis Scatter Diagram Pictorial representation of a simple regression Positive Relationship Data goes upward in an oval shape Negative Relationship Data goes downward in an oval shape No relationship Data neither goes upward nor downward Mellott & Associates LLC

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Positive Correlation Mellott & Associates LLC

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Negative Correlation Mellott & Associates LLC

No Relationship or Correlation
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Multiple Regression in Health Care Quality
Many examples where multiple regression could be an important tool: Factors related to compliance with medication regime Factors related to infections Factors related to high cholesterol Factors related to flexibility & strength Mellott & Associates LLC

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Multiple Regression Pareto diagram Cause & Effect diagram Mellott & Associates LLC

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Pareto Diagram What is it: Pictorial representation similar to multiple regression When used: When you want to determine where to start to get the biggest ‘bang for your buck’ What it will tell you: Where you should start in your improvement efforts Mellott & Associates LLC

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Cause & Effect Diagram What is it: Pictorial representation similar to multiple regression When used: When you want to determine where to start to get the biggest ‘bang for your buck’ What it will tell you: Where you should start in your improvement efforts Mellott & Associates LLC

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Cause & Effect Use when “bad” things happen to determine how it happened Use when want “Good” results to determine what you need to do to get those results Mellott & Associates LLC

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Cause & Effect Diagram Effect Cause Mellott & Associates LLC

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Showplace of Medical Readiness Life Quality Improvement NTC Surgeon Time Community Wellness PAT Measurement Leadership Resources Wellness Focus Summer Turnover MASCAL/EPP Lack of Measurement Info Technology Youth Info Technology Community In-processing Soldier Assist Board NCO Corps Awards Program DRETS AMMED Council PT Test FSG Oasis of Care FSG Focus Focus Management Orientation Access Info Flow Info Technology Turnover Team Work Staffing Restraints Committed Staff EC Issues Customer Focus Lack of Measurement MC/CS Division Ambulatory Care Center Commitment to Vision Isolation Shallow Staffing Limited Access to Specialists Master Calendar Speed of Change Mentor Program Medical Records Soldier Assistance Board Admin CBO Info Technology Library Empowered Staff Clinical CBO Education Program CME OPD NCOPD SGT’s Time This is an example of using a Cause and Effect diagram as an annual organizational assessment. This is from Weed Army Community Hospital at Fort Irwin, California. It is at the National Training Center in the Mojave Desert. Their vision is to be an OASIS of CARE. The Four components of that vision are at the 4 corners of the drawing. The right side of the lines are their strengths and the left are their weaknesses (in red). World Class Service Professional Excellence Mellott & Associates LLC © M. Ellicott

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Summary You first need to know what kind of data you are working with Then you have to know the types of tools and statistics you can use with that kind of data Then you design the data collection and plan the analysis of that data Mellott & Associates LLC

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