### Epidemiological Tools

There are a variety of tools that an epidemiologist might have at his or her disposal. The most common tools that are used in the field are SAS, SPSS, EpiInfo, R, and many others. These require significant time and diligence to become proficient at each of these statistical tools. However, almost every office has Microsoft Excel, Numbers (the Mac equivalent), or Google’s Excel-like product.

Often times, epidemiological calculations can seem/appear intimidating. However, if you let the excel document do the work for you then you do not have to worry about making errors in simple math. Please download the attached Microsoft Excel spreadsheet. You will be doing the following:

**Calculating:**

- Crude Mortality Rate
- Age-Specific Mortality Rate
- Age-Adjustment (using the direct method)
- Prevalence
- Incidence Density

**Graphing:**

- Incidence and Prevalence

You will need to go to the

Census Bureau

(https://data.census.gov/) then click on Advanced Search then click on Geography. In the area marked state, county, or place, type your community or a community near you and select enter. You are going to want information from a table that contains Age and Sex in the title.

Please see attached file

## Morbidity Measures

Pop

1

200

400

200

100

Year

Number Sick

Total Pop

Incidence

Prevalence

900

400

200

400

Example: Open Cohort (City, State, Zip Code etc) | ||||||||||||||||||||||||||||||||||

Year | Number Sick | Total | Incidence | Prevalence | ||||||||||||||||||||||||||||||

200 | 900 | 890,750 | 101.0 | 4 | 101.0384507438 | |||||||||||||||||||||||||||||

2002 | 400 | 908,830 | 44.01 | 143.0410527821 | ||||||||||||||||||||||||||||||

2003 | 920,6 | 23 | 21.72 | 162.9331441861 | ||||||||||||||||||||||||||||||

2004 | 930,517 | 42.99 | 204.1875645474 | |||||||||||||||||||||||||||||||

2005 | 100 | 939,605 | 10.64 | 212.855402004 | ||||||||||||||||||||||||||||||

2006 | 300 | 948,844 | 31.62 | 242.4002259592 | ||||||||||||||||||||||||||||||

2007 | 600 | 956,749 | 62.71 | 303.1098020484 | ||||||||||||||||||||||||||||||

2008 | 963,160 | 20.76 | 321.8572199842 | |||||||||||||||||||||||||||||||

2009 | 975,122 | 10.26 | 328.1640656246 | |||||||||||||||||||||||||||||||

Problem !: Open Cohort | This is the space where you should place your chart! | |||||||||||||||||||||||||||||||||

2012 | ||||||||||||||||||||||||||||||||||

2013 | ||||||||||||||||||||||||||||||||||

2014 | ||||||||||||||||||||||||||||||||||

2015 |

Formulas in Excel can be useful. Most epidemiological measures of incidence and prevalence are simple formulas that you can program in excel. Please visit this Microsoft Overview:

https://support.office.com/en-us/article/overview-of-formulas-in-excel-ecfdc708-9162-49e8-b993-c311f47ca173

Once you have finished the material, you will be ready for our first step. Incidence and Prevalence. The generic formula for both incidence and prevalence is sick/total population x some population multiplier, which can range from 100, 1,000, 10,000, 100,000, or even 1,000,000.

https://support.office.com/en-us/article/overview-of-formulas-in-excel-ecfdc708-9162-49e8-b993-c311f47ca173

Figure 1: Incidence and Prevealence of Herpes 2001 – 2009

Incidence 2001.0 2002.0 2003.0 2004.0 2005.0 2006.0 2007.0 2008.0 2009.0 101.0384507437553 44.01263162527646 21.72441922480755 42.98685569420011 10.64277010020168 31.61742077728267 62.712372837599 20.76498193446572 10.25512705076903 Prevalence 2001.0 2002.0 2003.0 2004 .0 2005.0 2006.0 2007.0 2008.0 2009.0 101.0384507437553 143.0410527821485 162.9331441860566 204.1875645474505 212.8554020040336 242.4002259591672 303.1098020483951 321.8572199842186 328.164065624609

Years

Rate Pper 100,000 Population

In this example, let’s assume that once you are infected with this disease you have it for life. Also, a fundamental assumption of this table will be that no one dies in this 9 year time window.

Click on each incidence and prevalence window to see where I inserted the formula.

Incidence = (Number Sick Cell/TotalPopulation Cell)*100,000

Prevalence is a little more different. Because people do not die from this disease and for this example, no one is dieing we have to add the previous years numbers for total diseased.

If we were trying to calculate the prevalence for 2002, we would have to enter the number from 2001 + 2002. Please click on the cell to see how I wrote the formula.

In the chart above, please find the population data from your town for the years 2012-2013. Using Excel formula complete the table. Once your table is complete, please visist the following link:

https://support.office.com/en-us/article/create-a-chart-from-start-to-finish-0baf399e-dd61-4e18-8a73-b3fd5d5680c2#OfficeVersion=Windows

You will need to create a chart based on the data you generated. Please see my example to the right of these instructions.

## Mortality Measures

& Age Specific Rate (

)

ASR

4

23

231,158

231,158

Total Crude Mortality Rateare calculated by multiplying the raw ASR X Standard Pop

Age GroupDeaths

Total Population

Expected Deaths

4

231,158 15 – 19

23

73,200 20 – 34

500

231,158 35 – 54

250

231,158 55+

1000

211,895 Total

1777

978,569

= Expected Deaths / Standard Population x 100,000

Adjusted Mortality Rate Age GroupDeaths

Total Population

ASR*

Expected Deaths

4

231,158

0.000017304

15 – 19

23

73,200

0.000314208

20 – 34

500

231,158

0.002163023

35 – 54

250

231,158

0.001081511

55+

1000

211,895

0.004719319

Total

1777

978,569

Example 1: | Crude Mortality Rate | ASR | ||||||||||

Age Group | Deaths | Total Population | ||||||||||

0 – 14 | 231,158 | 1.73 | ||||||||||

15 – 19 | 73,200 | 31.42 | ||||||||||

20 – 34 | 500 | 216.30 | ||||||||||

35 – 54 | 250 | 108.15 | ||||||||||

55+ | 1000 | 211,895 | 471.93 | |||||||||

1777 | 978,569 | |||||||||||

181.59 | ||||||||||||

Example 2: Age-Adjusted Rate (Direct Method) | Expected Deaths | |||||||||||

ASR* | Standard Population ^ | |||||||||||

0.000017304 | 56,100,000.00 | 970.76 | ||||||||||

0.000314208 | 23,100,000.00 | 7258.20 | ||||||||||

0.002163023 | 69,300,000.00 | 149897.47 | ||||||||||

0.001081511 | 85,800,000.00 | 92793.67 | ||||||||||

0.004719319 | 92,400,000.00 | 436065.03 | ||||||||||

326,700,000.00 | 686985.14 | |||||||||||

* we leave the ASR in decimal form and do not multiply it by 100,000 for this method | ||||||||||||

^ the standard population is usually the standard population for the United States. | ||||||||||||

However, it can really be whatever population you want it to be. | ||||||||||||

Adjusted Mortality Rate | ||||||||||||

210.28 | ||||||||||||

Your job is to use the Example 2 chart except for the standard population. Replace the standard population | ||||||||||||

data with data points from the American FactFinder. | Then calculate the adjusted rate. | |||||||||||

Your Population | ||||||||||||

In this exercise, we will be exploring how to calculate crude mortality, age-specific mortality, and direct age-adjustement. This exercise will require you to have access to demographic data from American FactFinder. Please work on the morbidity assignment prior to tackling this assignment. I am going to assume you already know how to use Excel formulas, as they were used extensively in the morbidity tab.

As with the previous tab, I will provide you examples. Remember:

Age Specific Mortality (ASR): Total Died in that Age Category/Total in that Age Category x 100,000

Crude Mortality Rate: All deaths/Total Population x 100,000

Age-adjustment is odd, you have to calculate the ASR first and not multiply it by 100,000. Then you multiply it by a standard population, or a population you are attempting to compare it to.

Now if you look at the ASR, you will see that clearly 55+ have the highest age specific rate. However, remember that population covers a lot of people and can be prone to a high rate or mortality already.

Calculating an age specific adjustment be useful to see if the crude rate increases or decreases.

http://sphweb.bumc.bu.edu/otlt/MPH-Modules/EP/EP713_StandardizedRates/EP713_StandardizedRates_print.html