Skip To Content

Calculate malaria incidence rates

In the previous lesson, you added malaria data. In this lesson, you'll calculate malaria incidence rates using the population estimate and malaria incidence data you appended in previous lessons. To do this, you'll create new attribute fields and use the field calculator to calculate the rate per 1,000 population.

Calculate the rate

Now that you have population and malaria incident count in one layer, you'll create new attribute fields to calculate the rate. In this lesson, you cleaned and formatted malaria incidence data and loaded it into ArcGIS Pro. In the next lesson, you will calculate the malaria incidence rate from the population estimate and malaria incidence data you have added so far.

  1. Open the DRC_Country attribute table.
  2. At the top of the attribute table, click Add to open the Field view.

    Add new field from attribute table

  3. Click the last row in the Field view to create a new field. You'll need to add four new fields:

    Field NameAliasData Type

    Incidence2000

    IncidenceRate2000

    Long

    Incidence2005

    IncidenceRate2005

    Long

    Incidence2010

    IncidenceRate2010

    Long

    Incidence2015

    IncidenceRate2015

    Long

    New incidence fields added

  4. In the Fields tab, in the Changes group, click Save.
  5. Close the Field view.

    You'll now calculate the incident rates for the new fields you just created. The incident rate is calculated with the following equation: (malaria incidence rate/total population) * 1000 = Incidence rate per 1,000 population.

  6. In the DRC_Country attribute table, right-click IncidentRate2000 and choose Calculate Field.

    Open the Calculate Field tool for IncidenceRate2000

    The Calculate Field tool opens.

  7. For Input Table, choose DRC_Country.
  8. For Field Name, choose IncidenceRate2000.
  9. For Incidence2000 =, type round((!F2000! / !SUM!)*1000,0).

    Calculate Field tool running for IncidenceRate2000

    The expression contains three parts. The round function takes two inputs, which are separated by a comma. The first input is the number to round and the second is how many spaces to round to. In this case the calculated incidence rate is the number((!F2000!/ !SUM!)*1000), which will be rounded to 0 spaces.

    The second part is the !F2000!, which corresponds to the 2000 incidence count. When calculating the rate for other years, you'll change this number to reflect the year. The incidence rate year attributes can also be selected from Fields.

    The third part is the !SUM!, which corresponds to the population estimate attribute you calculated earlier using Zonal Statistics.

  10. Click the green checkmark to validate the expression.

    The expression should return valid. If not, check your equation for any errors.

  11. Click Run.

    In the DRC_Country attribute table, the value for the IncidenceRate2000 attribute has now been calculated as 303. This indicates that 303 per 1,000 people experienced a case of malaria in 2000.

  12. Repeat the previous steps (6 through 11) to calculate the country incidence rate for 2005, 2010, and 2015. Change the names and variable usage accordingly.

    Incidence rate attributes calculated for each year

    Tip:

    To calculate the incidence rates for 2005, 2010, and 2015 use the following expressions:

    Incidence2005 = round((!F2005! / !SUM!)*1000,0)

    Incidence2010 = round((!F2010! / !SUM!)*1000,0)

    Incidence2015 = round((!F2015! / !SUM!)*1000,0)

    Ensure that the Field Name matches the year you are calculating for.

  13. Press Ctrl+S to save your project.

    Now that you have the incidence rate calculated for each year at the country level, you'll calculate it at the administrative level.

  14. Open the DRC_Admin attribute table.
  15. At the top of the attribute table, click Add to open the Field view table.
  16. Add four new fields as described in the following table:

    Field NameAliasData Type

    Incidence2000

    IncidenceRate2000

    Long

    Incidence2005

    IncidenceRate2005

    Long

    Incidence2010

    IncidenceRate2010

    Long

    Incidence2015

    IncidenceRate2015

    Long

    Tip:

    To add new fields, on the DRC Admin attribute table, click Add.

    Add new incidence year attributes in the Fields view

  17. Save your edits and close the Fields view.

    Next, you'll calculate the incident rates for the new fields you just created.

    Tip:

    The incident rate is calculated with the following equation: (malaria incidence rate/total population) * 1000 = Incidence rate per 1,000 population.

  18. In the DRC_Admin attribute table, right-click IncidentRate2000 and choose Calculate Field.
  19. For Input Table, choose DRC_Admin.
  20. For Field Name, choose IncidenceRate2000.
  21. For Incidence2000 =, type round((!F2000! / !SUM!)*1000,0).
  22. Click Run.
  23. Repeat the previous steps to calculate the country incidence rate for 2005, 2010, and 2015. Change the names and variable usage accordingly.
    Tip:

    To calculate the incidence rates for 2005, 2010, and 2015 use the following expressions:

    Expression Incidence2005 = round((!F2005! / !SUM!)*1000,0)

    Expression Incidence2010 = round((!F2010! / !SUM!)*1000,0)

    Expression Incidence2015 = round((!F2015! / !SUM!)*1000,0)

    Ensure that the Field Name matches the year you are calculating for.

    Incidence rate per 1,000 calculated for administrative regions

  24. Save your project.

Share the Excel file

Now that you have calculated the incidence rates for both geographic scales, you'll export the data for sharing. Since incidence rate at the country level will be used for SDG reporting, you'll export it as an Excel sheet. Incidence data at the administrative region level 1 will be used to assess the situation within the country, which you will share as a web map in the next section.

  1. In the Analysis tab, in the Geoprocessing group, click Tools. Search for and choose the Table To Excel tool.
  2. For Input Table, choose DRC_Country.
  3. For Output Excel File, type CongoDRC_MalariaRates.
  4. Check Use field alias as column header.

    Table To Excel tool

    Note:

    You can click the browse button to save the Excel file in a specific location. Otherwise it will save the file in your project folder.

  5. Click Run.

The DRC_Country attribute table with population, incidence counts, and incidence rates has now been exported as a spreadsheet in your project folder. This attribute table can be shared for further analysis, updated with recent or locally collected data, or used in further spatial analysis.

In this lesson, you calculated malaria incidence rates; created maps to visualize incidence trends over time; and edited, updated, and exported a spreadsheet containing the calculated rates. In the next lesson, you'll learn how to share your data as a web map and communicate trends using smart symbology.