Iowa Cancer Incidence Data
VitalWeb Wizard
Online Help

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Table of Contents

  1. Introduction

    Wizard Starts in "Beginner" Mode

    Wizard also Runs in "Expert" Mode

  2. Basic Table Layout

    Main Statistic

    Table Axes (Rows and Columns)

    Statistic / Axis Conflicts

  3. Data Variables

    Categorical Variables

    Range Variables

    Statistic / Variable Conflicts

    Other Settings

  4. Chart Settings

    Bar Chart Coloring

    Bar Chart Layout

    Line Chart Settings #1

    Line Chart Settings #2

    Pie Chart Coloring

    Pie Chart Layout

    Tabular Charts / Chart Links

  5. Map Settings

    Map Coloring

    Map Layout

    Map Color Palettes

  6. Producing and Using Results

    Getting Results

    Viewing Results

    Printing Results

    Saving Results

    When Charts and Maps are Made

  7. Other Information


    County Groupings

    95% Poisson Confidence Limits

    Age Adjustment Standards

    Statistical Methods

    Confidence Intervals

    Data Sources and Limitations

    Links to Related Resources

    Whom to Contact

    Legal Information

Wizard Starts in "Beginner" Mode

Screenshot of Basic Wizard

Instructions for Using Step-by-Step Mode:

1. Make selections - At each step, make selections.
2. Go to next step - Click "Next Step" to move forward.
3. Make output - At last step, produce output table (or map).
4. View output - Results appears in the same window as the wizard.
5. Return to wizard - Click browser "Back" button after viewing output.
6. Continue - Click "Restart" to start wizard again at first step.

• To go back a step, click "Previous Step" (not browser "Back" button).
• You may switch to Jump-to-Step mode (see next page) at any time.

Wizard also Runs in "Expert" Mode

Screenshot of Advanced Wizard

Instructions for Using Jump-to-Step Mode:

1. Jump - Click on step name from top or right.
2. Select - At the chosen step, make selections.
3. Make Output - When ready, click "Make Table".
4. View Output - Results appear in current window.
5. Return to Wizard - Click browser "Back" button.
6. Continue - Keep making selections and output.

• To go back a step, click step name, not "Back" button.
• You may switch to Step-by-Step mode at any time.
• You may switch to designing a map at any time.

Main Statistic

Main Statistic - The basic numerical result in the output.

Main statistics include: Cancer Cases | Cancer Incidence Rate | Age-Adjusted Incidence Rate | Standardized Morbidity Ratio

Selecting - Click on desired setting, such as Cancer Cases.

Example Statistic Selector (above)

Table Axes (Rows and Columns)

Year 0-19 20-39 40-59 60-79 80+
1990 100 120 140 160 180
1991 120 140 160 180 200
1992 140 160 180 200 220

Rows - Horizontal lines of data, such as 1991 row.
Sorting - Can sort rows low to high, or high to low.
Columns - Go up and down, such as 0-19 column.
Multi-Tables - "ByVar". Make a series of tables.

Selecting - Click on desired setting, such as "Year".

Example Row, Column, or ByVar Selector (above)

Statistic / Axis Conflicts

If a conflict between Main Statistic and Axis Variable:

• Vitalnet alerts you of the conflict (mismatch).
• Vitalnet prevents contradictory results.

Examples of conflicting settings:

• Race rows -- race columns
• Year rows -- year columns
• Age-adjusted rates -- age rows

Selecting Data Variables

Data variables include - age, cancer diagnosis, county of residence, race, stage, year.

Selecting - Click on one or more values.

Example Data Variable Selector (Age) (above)

Selecting Data Variable Groupings

Certain data variables allow different "groupings".
For example, 5-year or 10-year age groups.

To change the grouping in actual interface:

1. Click on desired grouping.
2. Click on "Select" button.

Example Data Grouping Selection (above)

Statistic / Variable Conflicts

No Left Turn Sign Sometimes, a conflict exists between a variable and a population-based rate. Vitalnet automatically prevents this from producing misleading output.

This is best shown with an example: Suppose there are 408,000 births, and the population is 12,000,000 females. Thus, the birth rate is 34 births per 1,000 females (408,000 / 12,000,000).

Now, suppose we try limiting the analysis to women with 12 years education. We know there are 108,000 births to such women. The result would seem to be 9 births per 1,000 such women (108,000/ 12,000,000). But of course this is totally wrong, because the denominator is not adjusted. And we do not have the population denominator data for women with 12 years education, so there is no easy solution.

To resolve this problem, when Vitalnet makes a rate calculation, it automatically prevents spurious results from being produced, by automatically adding all categories to demographic variables that are not included in the population data set.

So, for example, if you try to calculate a birth rate for women with 12 years of education, Vitalnet simply ignores the limitation to 12 years of education. Instead, it includes all levels of education, so the numerator and denominator match up. And it correctly reports that all levels of education were analyzed.

In contrast, if you try to calcuate a cesarean rate for women with 12 years of education, this does not require population data, only requires information on the births, so Vitalnet calculates the cesarean rate, limited to women with 12 years of education.

Other Settings

Other Settings include the following options:

Statistic Modifiers:
Age-Adjust Standard - Standard Population to Use
SMR Standard - Standard for Calculating SMR

Secondary Statistics:
Cell Confidence Level - Set Level, or Turn Off
Cell Suppression - Hide Result if Low Count
Table Percents - Row or Column Percents
Trend Algorithm - Trend Analysis Method
Trend Confidence - Set Level, or Turn Off

Miscellaneous Details:
Decimal Digits - Example: Two in 5.78
HTML Line Style - Line Style for Output HTML
HTML Output Font - Text Font for Output HTML
HTML Padding - Padding for Output HTML Table
Spreadsheet Format - Spreadsheet Data Format
Tabular Chart - Chart Width, or Omit Chart
Unique ID - Put ID on Maps and Charts?

Bar Chart Coloring

• Background color behind the chart.
• Color palette to use for the bars.
• First color in palette to use for bars.

Below are shown the settings, with examples:

Background Color for Chart (20 options)


Grey 95

Lemon Chiffon

Light Cyan

Color Palette for Bars (4 options)

Bright Colors

Subdued Colors

Bright + Subdued

Black + White

First Color in Palette to Use (10 options)

A Forward

D Reverse

E Forward

J Reverse

Bar Chart Layout

Vertical or Horizontal Bars

Vertical Bars


Stacked Bars?

Stacked Bars

Not Stacked

Height of Each Bar (9 options)

2 cm High

4 cm High

Width of Each Bar (8 options)

0.2 cm Wide

0.6 cm Wide

Include Grid Lines?

Include Grid

Omit Grid

Font Size for Chart Text (8 options)

10 pt Font

14 pt Font

Line Chart Settings #1

Eight ways to customize Vitalnet line charts:

Background Color for Chart (20 options)

Alice Blue

Light Yellow

Include Data Point Symbols? (2 options)

Include Symbols

Omit Symbols

Radius for Chart Symbols (10 options)

1.0 mm Radius

1.4 mm Radius

Line Chart Height (9 options)

4.0 cm (Not Shown)

7.0 cm (Not Shown)

Line Chart Settings #2

Width of Lines (3 options)

Thin Lines

Thick Lines

Include Grid Lines? (2 options)

Include Grid

Omit Grid

Colored Lines, or Black + White (2 options)

Colored Lines

Black + White Lines

Font Size for Chart Text (8 options)

10 pt Font (Not Shown)

12 pt Font (Not Shown)

Pie Chart Coloring

Three settings for customizing pie chart coloring:

• The background color behind the chart.
• The color palette to use for the pie chart.
• First color in palette to use (for slice #1).

Background Color for Chart (20 options)

Cornsilk Background

Grey Background

Light Cyan

Color Palette for Pie Chart (3 options)

Bright Colors

Subdued Colors

Mixed Colors

Slice #1 Color to Use (10 options)

Color A for #1

I Forward

F Reverse

Pie Chart Layout

Four settings for customizing pie chart layout:

Slice #1 Clock Position (12 options)

Slice #1 at Noon

Slice #1 at 3:00

Slice #1 at 6:00

How to Label Pie Chart (9 options)

Line + Label

Label Only

Use Legend

How to Display Slice Percents (3 options)

Percent After Label

Under Label

Omit Percents

Pie Chart Radius (9 options)

3.0 cm (Not Shown)

4.0 cm (Not Shown)

5.0 cm (Not Shown)

Tabular Charts / Chart Links

Tabular chart

A "tabular chart" is a convenient way of making comparisons.

The tabular chart is always made, unless turned off from the "Other Settings" menu. Also, you may specify the width of the columns within the chart.

Chart links: Note the links below the tabular chart. The links connect to additional graphical and data output formats. The example above links to bar chart, text, database, and spreadsheet formats.

Map Coloring

Color Combination (36 options)




Number of Colors (8 options)

3 Colors

5 Colors

7 Colors

How to Set Ranges (3 options)

Equal Ranges

Equal Counts

Natural Breaks

Map Layout

Boundaries to Display (2 options)

County Boundaries

HSR Boundaries

Border Counties

Cell Suppression (14 options)

Suppression Off

Suppress if < 10 Events

Suppress if < 30 Events

Map File Format (PNG, PDF, SVG, GIS)

PNG Map (Imports Best)

SVG Map (Prints Best)

GIS Map (Interesting)

Map Color Palettes

1 2 3 4 5 6 7 8 9   Diverging Palette    BW   CB 
                                                        Brown-BlueGreen   - Y
                                                        Pink-Green   - Y
                                                        Purple-Green   - Y
                                                        Purple-Orange   Y Y
                                                        Red-Blue   - Y
                                                        Red-Grey   - -
                                                        Red-Yellow-Blue   - Y
                                                        Red-Yellow-Green   - -
                                                        Spectral   Y -
1 2 3 4 5 6 7 8 9   Sequential Palette    BW   CB 
                                                        Blue   Y Y
                                                        Blue-Green   Y Y
                                                        Blue-Purple   Y Y
                                                        Green-Blue   Y Y
                                                        Green   Y Y
                                                        Grey   Y Y
                                                        Orange   Y Y
                                                        Orange-Red   Y Y
                                                        Purple-Blue   Y Y
                                                        Purple-Green   Y Y
                                                        Purple-Red   Y Y
                                                        Purple   Y Y
                                                        Red-Purple   Y Y
                                                        Red   Y Y
                                                        Yellow-Green   Y Y
                                                        Yellow-Blue   Y Y
                                                        Yellow-Brown   Y Y
                                                        Yellow-Red   Y Y

All palettes are OK for color printing. BW - OK for black and white printing? CB - OK for red-green color blindness?

References for Vitalnet map color palettes - • LW Pickle, M Mungiole, GK Jones, AA White, "Atlas of United States Mortality", National Center for Health Statistics, 1997. • CA Brewer, "Color Use Guidelines for Mapping and Visualization", in "Visualization in Modern Cartography", Elsevier, 1994. • ColorBrewer web site showing color palettes.

Getting Results

Go Sign To produce results:

• Click "Make Map" or "Make Table".
Step-by-Step Wizard - Last step.
Jump-toStep Wizard - Anytime.

• Program sends query to server.
• Results should return in seconds.
• Results appear in window Wizard is running in.

Viewing Results

Binoculars After you click "Make Map" or "Make Table", results are sent to the window where the Wizard is running.

To view results:

1. Scroll results - Use scroll bar, PgUp, PgDn, etc.
2. Print or Save results - Sends to printer or disk.
3. Click on footnote links - Access charts and data files.

If graphics do not display in output, refresh the browser.
To do another analysis, click browser "Back" button.

Printing Results

Printer To print results from your browser, use one of the following methods:

Press CTL-P - Hold down Control key, and press 'P' key.
Use Browser Icon - Click on Print Icon (if available).
Use Browser Menu - Select "File / Print" (if menu available).

If output table is too wide or long, here are two ways to make it fit:

Use fewer rows or columns. Also makes it easier to understand.
Change browser font size. Typical command is: View / Text Size.

How to print from a spreadsheet or word processor:

1. Click on link for desired format in output footnotes.
2. Download and import the data file:
  • CSV / TSV / DIF for spreadsheets, such as Excel or StarOffice.
  • ASCII for word processor, such as Word or WordPerfect.
3. Format and print from within your spreadsheet or word processor.

Saving Results

File Cabinet To save results displayed in your browser, do one of the following:

Press CTL-S - Hold down Control key, and press 'S' key.
Use Browser Menu - Select "File / Save" (or equivalent).

To save an alternate data format, click on a footnote link:

ASCII text - Import into word processing software.
CSV/TSV/DIF format - Import into spreadsheet software.
dBASE III - For database, GIS, mapping, stats software.

To save a map as an image file, minus any surrounding text:

1. Position cursor over map, using your mouse.
2. Press right mouse button to bring up popup menu.
3. Select "Save" option from popup menu.
4. Specify directory (folder) to save file.

Here are some suggestions on naming files:

Memorable - Select a name that will remind you of the content.
Organized - Organize files into project directories (folders).
Linkable - Use provided unique ID for data files, such as "112jdhkm.dbf".

When Charts and Maps are Made

Vitalnet is smart about making output. Whenever you make a table, Vitalnet usually makes one or more accompanying charts. But it only produces the charts that make sense. If a chart would look terrible, or not be epidemiologically valid, the software does not make it.

Vitalnet avoids making misleading or useless charts. To prevent misinterpretation and embarassing results, Vitalnet intelligently decides when it appropriate to make a chart, as explained below:

Bar charts are only made if the following conditions are met:

• 1 to 20 rows (groups of bars).
• 1 to 10 columns (bars per group).
• No suppressed results (for stacked bar chart).

Line charts are only made if the following conditions are met:

• Range rows (such as age or year).
• No breaks in ranges (not 2000, 2002).
• Rows not sorted. No suppressed results.
• No more than 10 lines (10 columns).

Pie charts are only made if the following conditions are met:

• Cumulative data (counts, some rates).
• One set of numbers (one row or column).
• 2 to 9 pie slices. No suppressed results.

Time trend maps (that cycle from map to map) are only produced when all selected year ranges are the same width. For example, 1995-1996, 1997-1998, 1999-2000 is OK. But 1995-1996, 1997-1998, 1999 is not OK. Also, at least two year ranges are required. So if you just have 1995-1996 (a single range) selected, Vitalnet does not make a series of time trend maps.

Time trend analysis, when making a table with year rows, is only carried out when: 1) at least three year ranges are selected, 2) there are no gaps in the ranges, 3) the ranges are the same width, and 4) the rows are not sorted. When these conditions are met, the time trend analysis is epidemiologically valid.


Age-adjusted death rate - Deaths per 100,000 population, adjusted to a standard population (such as US 1940 or US 2000), by the direct method. Age-adjusted rates are often better for making comparisons than unadjusted rates, because they adjust for differences in age distribution between populations. An age-adjusted rate is a summary synthetic measure. Besides calculating overall age-adjusted rates, it is also recommended to compare age-specific rates.

Age-adjustment standard - A standard population for calculating an age-adjusted death rate. The 1940 and 2000 US Census population are the most common standards.

Area set - One or more areas combined.

ASCII file - A text file, with only alphabetical, numerical, and punctuation characters, like you would see in normal text. Vitalnet can produce output in ASCII format.

CDC - Centers for Disease Control and Prevention. US federal health agency.

Cell - A space for a single numerical result in a table, at a row-column intersection.

Cell suppression - An asterisk "*" is placed in cells with fewer events (such as deaths) than a limit set by the user. Row / column totals with exactly one suppressed cell in the row / column are also suppressed. If more than one cell in the row / column is suppressed, the row / column total may be displayed.

Columns - Vertical groupings of data in a Vitalnet table, such as a column for each race group.

Confidence interval (confidence limits) - A range of values within which the true value of a variable is thought to lie, with a specified level of confidence. For a result of 23.5, a confidence interval might be (23.1-23.9). The smaller the interval, the more reliable the result, so 23-24 is more reliable than 13-34. If the 95% confidence intervals do not overlap, there is probably a statistically significant difference. Vitalnet uses several methods to calculate confidence intervals. The output table documents which method was used.

Confidence level - The likelihood that the true value of a variable is within a confidence interval. For example, for confidence intervals at the 95% level, we are statistically 95% certain that the actual value of the variable is within the interval.

CSV format - Comma-separated-value format. CSV files are readily imported into spreadsheet software. Each output item is separated by a comma from surrounding items, and each output text item is surrounded by "double quotes". A comma-separated-value file has "csv" extension. Similar to TSV format.

Data warehouse - A software system, such as Vitalnet, making large complex databases readily available for querying and analysis. A related term is "data mining", finding unexpected relationships in a data set, for further study. Data mining is similar to exploratory data analysis. Vitalnet is excellent at data mining. Of course, keep in mind that the more you look, the more unusual events you will find, just by chance.

dBASE III format - A widely used file format originally for the database software of the same name. Files in dBASE III format may be readily imported into almost any data analysis, graphing, mapping, or other presentation software. Uses dbf extension. Suppressed cells are represented as the number "-1".

DIF format - Data interchange format. DIF files are readily imported into spreadsheet software. The DIF format is too complex to explain in this glossary. Has "dif" extension.

Denominator - The number on the bottom of a fraction. Population data are often referred to as "denominator data", as they are used as denominators to calculate population-based rates.

Export - Produce output that can be read into other computer programs. Vitalnet produces ASCII text (txt), comma-separated-value (csv), HTML (htm), and dBASE III (dbf) files for export.

Filter variable - A variable solely used to filter which records are included in the output. For example, for a single table with race rows and sex columns, age 10-19 is a filter variable.

FIPS Code - FIPS = "Federal Information Processing Standards". A five-digit number which uniquely identifies counties, territories, and certain other areas in the United States. States have two-digit FIPS codes.

Footer - Last part of a Vitalnet table. Lists less important details of the analysis, such as the date produced, and data sources. Also contains a unique ID to assist in keeping track of analyses.

Header - First part of a Vitalnet table. Lists key analysis parameters, such as years analyzed.

Import - Read information into a computer program. ASCII text, CSV, TSV, DIF, HTML, and dBASE III files from Vitalnet are easily imported into word processing, spreadsheet, data analysis, mapping, graphing, and other presentation software programs.

Least-squares - A standard method for fitting the best straight line to a set of points. Produces a Y-intercept and a slope defining the least-squares line.

Multiple age groups - One age group for each table row (or column). Example: 0-19, 20-59, 60-99+.

Natural Breaks - Method for determining map ranges. Minimizes "squared deviations from class means".

NCHS - National Center for Health Statistics. US health statistics agency. Part of the CDC.

Population - The number of people living in an area.

Rows - Horizontal lines in a Vitalnet table, such as a row for each race group.

Row sort settings - Vitalnet rows may be sorted in ascending or descending order.

Set - A combination of one or more things. For example, several areas may be combined into an area set.

Single age group - Only one age group (30-49, for example) is selected. A single age group is used for tables that do not have age columns or age rows.

Standardized mortality ratio (SMR) - The ratio of the expected number of deaths to the observed number of deaths. The expected number of deaths is derived by applying a standard set of rates (usually state or national rates) to a population. SMRs help assess whether the mortality in a population is higher than expected.

Statistic (Main Statistic) - The basic type of numerical result displayed in a table, chart, or map. For example, birth rate, death rate, population, pregnancy rate, etc.

Table - A set of results produced by Vitalnet. A table has several parts:
  1. Header - basic analysis settings
  2. Data section - numerical results
  3. Bar graphs - horizontal charts
  4. Footer - other analysis settings

Tabular chart - A section of a Vitalnet table. Gives an scaleable graphical representation of the data. May be omitted from the output table.

TSV format - Tab-separated-value format. TSV files are readily imported into spreadsheet software. Each output item is separated by a tab from surrounding items, and each output text item is surrounded by "double quotes". A tab-separated-value file has "tsv" extension. Similar to CSV format.

Unknown Values - Unknowns are automatically inserted into a Vitalnet table. For example, a separate row (or column) for unknown race. The rate is assigned as zero for an unknown category, since there is no population denominator to use. Some fields, such as sex for certain data sets, are never unknown, so unknowns are left off the table. When, such as for age-adjusted rates, the unknown variable (age) is different from the rows or columns, the number of unknowns for age is shown below the table.

Vitalnet / VitalPro / VitalWeb - Vitalnet is data warehouse / data analysis software for analyzing health data sets. VitalPro is a Vitalnet system that runs directly on a PC, for example VitalPro for Win32. VitalWeb is a Vitalnet system that runs over the internet, for example VitalWeb Ajax.

Windows - Microsoft PC operating systems. VitalPro runs under any version of Windows.

World Wide Web (WWW) - A widely used part of the internet that may be easily accessed with a web browser. Vitalnet runs on the WWW.

County Groupings

Region 1: Boone, Calhoun, Carroll, Dallas, Greene, Grundy, Hamilton, Hardin, Jasper, Marshall, Polk, Poweshiek, Story, Tama, Warren, Webster
Region 2: Allamakee, Bremer, Butler, Cerro Gordo, Chickasaw, Emmet, Fayette, Floyd, Franklin, Hancock, Howard, Humboldt, Kossuth, Mitchell, Winnebago, Winneshiek, Worth, Wright
Region 3: Buena Vista, Cherokee, Clay, Crawford, Dickinson, Ida, Lyon, Monona, O=Brien, Osceola, Palo Alto, Plymouth, Pocahontas, Sac, Sioux, Woodbury
Region 4: Adair, Adams, Audubon, Cass, Clarke, Decatur, Fremont, Guthrie, Harrison, Madison, Mills, Montgomery, Page, Pottawattamie, Ringgold, Shelby, Taylor, Union
Region 5: Appanoose, Davis, Des Moines, Henry, Jefferson, Keokuk, Lee, Louisa, Lucas, Mahaska, Marion, Monroe, Muscatine, Van Buren, Wapello, Washington, Wayne
Region 6: Benton, Black Hawk, Buchanan, Cedar, Clayton, Clinton, Delaware, Dubuque, Iowa, Jackson, Johnson, Jones, Linn, Scott

Age Adjustment Standards

Age group 1940 US 1970 US 2000 US
0 to 0 15,343 17,151 13,818
1 to 4 64,718 67,265 55,317
5 to 9 81,147 98,204 72,533
10 to 14 89,208 102,304 73,032
15 to 19 93,670 93,845 72,169
20 to 24 88,007 80,561 66,478
25 to 29 84,277 66,320 64,529
30 to 34 77,789 56,249 71,044
35 to 39 72,495 54,656 80,762
40 to 44 66,742 58,958 81,851
45 to 49 62,697 59,622 72,118
50 to 54 55,114 54,643 62,716
55 to 59 44,383 49,077 48,454
60 to 64 35,911 42,403 38,793
65 to 69 28,911 34,406 34,264
70 to 74 19,515 26,789 31,773
75 to 79 11,422 18,871 26,999
80 to 84 5,881 11,241 17,842
85 to 99+ 2,770 7,435 15,508
Total Million Million Million

Statistical Methods

The "Main Statistic" (numerical outcome) is the basic type of number in a Vitalnet table. It is best understood by looking at the examples below.

Cases - The number of cancer cases.

Incidence Rate - Cases per 100,000 population. This rate may be used to compare the burden of disease between different groups.

Age-Adjusted Rate - The number of cases per 100,000 population, adjusted to a standard population (such as US 1940), by the direct method. Age-adjusted rates are often better for making comparisons than crude rates, because they adjust for differences in age distribution between populations. An age-adjusted rate is a single summary measure. Be aware that it may mask trends detectable by examining age-specific rates. Age-adjusted rates are synthetic rates that are only useful in comparison with other age-adjusted rates. Age-adjusted rates are used to compare one area or population to another because age distribution is controlled for in the calculations. Age-adjusted rates are not typically calculated for individual age ranges, such as 40-49, and Vitalnet does not do so.

Standardized Morbidity Ratio (SMR) - The ratio of the number of observed cases to the number that were expected. Also called indirect adjustment. An SMR greater than 1 indicates more events were observed than expected. The number expected is derived by applying age-specific standard rates for a general population to the population in the area under study. The standard rates can include all races, or only the races being studied in the smaller area (race-specific). Similarly, the standard rates can include both male and female, or only the sex being studied in the smaller area (sex-specific). A standardized morbidity ratio is a single summary measure. It may mask trends detectable by examining age-specific rates. Standardized morbidity ratios are not usually calculated for individual age ranges, such as 40-49, and Vitalnet does not calculate such rates.

Age-Adjusted Rate Methodology - 1) Determine age-specific rates in the Study population. (Set age-specific rate to zero if age-specific population is zero.) 2) Multiply age-specific rates by Standard age-specific populations, such as 1940 US. 3) Sum the results from the previous step. 4) Divide the sum by the total size of the Standard population.

SMR Methodology - 1) Determine the age-specific incidence rate for each age group in the Standard (State) population. The age-specific rates may be based on all races combined, or just on the races that are selected (race-specific). 2) For each age group, multiply the age-specific rate by the number of people in that group in the Study population. 3) Sum the results from the previous step. This is the expected number of cases. 4) Divide the actual number of cases observed by the number expected (SMR = observed / expected). For example, if 10 cases were expected in a county (based on the State rate), and 20 occurred, the SMR is 2.

Confidence Intervals

Definition - A "confidence interval" is a range of values within which the true value of a variable is thought to lie, at a certain "confidence level", such as 95%. A larger percentage (such as 99%) is more stringent than a smaller percentage (such as 80%). Use 95% if you are unsure.

Interpretation - The smaller the interval, the more reliable the result. Two results that overlap at the 95% level are less likely to be significantly different than results which do not overlap.

Methods - The method Vitalnet uses to calculate confidence intervals depends on the context. The method is listed in the footnotes to the table.

Z * Rate / Sqrt (Events) - This method is recommended by the NCHS. Technical Appendix of the Vital Statistics of the United States, Vol II, Mortality, Part A

Rothman and Boice - This method is for SMRs. Rothman KJ and Boice JD (1979): Epidemiologic analysis with a programmable calculator. NIH Publication No. 79-1649, Washington, DC: U.S Department of Health.

Poisson distribution - This method is valid if events are relatively rare, which usually applies to health events. Scientific Tables, Diem and Lentner (ed), Giegy, 1970, page 189.

95% Poisson Confidence Limits

Events Lo Factor Hi Factor Events Lo Factor Hi Factor Events Lo Factor Hi Factor
1 0.025318 5.571647 70 0.779549 1.263440 4,000 0.969250 1.031230
2 0.121104 3.612346 80 0.792938 1.244587 5,000 0.972473 1.027911
3 0.206224 2.922426 90 0.804118 1.229170 6,000 0.974857 1.025464
4 0.272466 2.560398 100 0.813640 1.216268 7,000 0.976711 1.023564
5 0.324697 2.333667 200 0.866209 1.143395 8,000 0.978207 1.022034
6 0.366982 2.176580 300 0.890041 1.116362 9,000 0.979446 1.020767
7 0.402052 2.060382 400 0.904401 1.100401 10,000 0.980496 1.019696
8 0.431729 1.970399 500 0.914267 1.089575 20,000 0.986189 1.013907
9 0.457263 1.898312 600 0.921584 1.081617 30,000 0.988716 1.011348
10 0.479539 1.839036 700 0.927291 1.075453 40,000 0.990224 1.009824
20 0.610826 1.544419 800 0.931904 1.070497 50,000 0.991254 1.008785
30 0.674696 1.427562 900 0.935734 1.066400 60,000 0.992014 1.008018
40 0.714415 1.361716 1,000 0.938980 1.062941 70,000 0.992606 1.007422
50 0.742219 1.318376 2,000 0.956653 1.044307 80,000 0.993082 1.006942
60 0.763105 1.287198 3,000 0.964536 1.036105 90,000 0.993477 1.006544

Data Sources and Limitations

VitalWeb Wizard uses data from authoritative sources.

Cancer incidence data - All cancer incidence data were provided by the NCI SEER Program - (

Links to Related Resources

Internet resources related to Cancer Incidence Data:

• Iowa data - Contacts to be added

Whom to Contact

For additional assistance with analyzing and interpreting the data, contact:

• Iowa data - Contacts to be added

Legal Information

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Documentation produced: "Apr 1 2023" - Contact EHDP