MTAS Benchmarking

Data Analysis & Empirical Decision Making (EDM)

Matthew Marshall

MPA , CMFO

City of Athens, TN

"For those of us who have
mistaken passion for a solution...
hope is not a course of action."

-Poet Buddy Wakefield

P-Values & Grouping.

Pearson's R

A statistical method used to determine coorelation/no correlation between to data sets.

Grouping

The practice of categorizing cities based on  population, MSA status, proximity to the interstate, and service population.

Micropolitan:

Athens, Paris, Crossville, Sevierville, and Springfield

Suburb:

Bartlett, Brentwood, Franklin, Goodlettsville, and Red Bank

Sub Major City:

Morristown, Cleveland, Kingsport, Greenville, and Tullahoma

Major City:

Knoxville, Chattanooga, and Murfreesboro

The Effects of Grouping

For Micropolitans a moderate and Major Cities a strong negative correlation was established between Inspections and Structure fires per 1,000 residents.

Micropolitans P= -0.50          Moderate Negative Relationship

Major Cities P= -0.98             Very Strong Negative Relationship

For Suburbs and Sub Major Cities we found only moderate correlation between Inspections and Structure fires, and in the case of Sub Major Cities a positive correlation per 1,000 residents.

Suburbs P= -0.08                   Very Weak Negative Relationship

Sub Major Cities P= 0.47      Moderate Positive Relationship

If we look at the correlation with all benchmarking cities we see a strong positive relationship, P= 0.55.

The Effects of Grouping

Pearson's R for all Cities = 0.55, but when you break down the cities into their groups you see a different story.

For Micropolitans we found no relationship correlations between the Number of Sworn Officers and TIBRS A crimes per 1,000.

Micropolitans P= 0.14

For Suburbs, Sub Major and  Major Cities we found a very strong correlation between Number of Sworn Officers and TIBRS A crimes per 1,000.

Suburbs P= 0.83

Major Cities P= 0.85

Sub Major Cities P= 0.58

Analysis

Question:

Council member X - "Police Chief Ziegler do you know why we have so many Robberies this year?"

Police Chief Ziegler - "It's how we measure time."

We use Z Tests and T-Tests to determine when a statistic becomes Statistically Significant and when it is just more/less than the year before.

Predictions

Procedure

1.  Establish the most statistically significant correlation.

2.  Determine a Line of Best fit (may or may not be linear).

4.  Review your results and determine if the Line of Best fit is            matching your results.

Predicting Using a Line of Best Fit.

Questions?

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# DAEDM

by monkndylan

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Public - 3/29/16, 1:02 PM