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Section 2: Background IV. An Overview of the Process Background Information on the Statistics |
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One number, by itself, usually means relatively little. This report seeks to compare Cortland indicators over time, to other counties in Upstate New York, and, where the data exist, to the state and federal objectives for 2006 and 2010. |
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The indicator numbers herein are usually expressed as rates -- the number of events per 1,000 or per 100,000 individuals per year. When the rate applies to a specific age group, the rate is called an age-specific rate. For example, the age specific teen pregnancy rate would be the number of teen pregnancies per 1,000 females in the 15 —19 year old age group in a given year. Even though there are fewer teens in Cortland compared to a larger county, the rate allows us to compare like units to like units. The 1997 teen pregnancy rate in Cortland County is 44 per 1,000 15-19 year old females. In Erie County, that rate is 78 per 1,000. Compared to Erie County, Cortland County has a lower rate of teen pregnancies among females 15 —19 year olds. |
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Some data are expressed as confidence intervals at specified levels. A confidence interval is a margin of error related to chance. For example, we might say that the percent of people who smoke cigarettes in Cortland County is 40.1% with a "confidence interval" of 22.7% to 57.6%; at a 95% level, we mean that there are 95 chances out of a 100 that the percentage of smokers in the population is somewhere between 22.7% and 57.6%. In general, the larger the sample drawn from a population, the smaller the confidence interval tends to be and thus the more reliable the rate is. |
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Small numbers of events, for instance, the number of cases of measles in Cortland, can be much more erratic over time than larger numbers of events. If the cases of measles in Cortland doubled in a year by going from 1 to 2, that would not be as statistically important as would be the doubling of cases of measles in the United States. Similarly, even small changes in the number of events occurring to Cortland's small Native American population could cause the rate to vary substantially from year to year. For this reason data from multi-year intervals are sometimes combined to give "rolled" averages. Rolled averages stabilize the rates and allow us to look at trends over time. For example, to report on hospitalizations of children due to asthma, the rates from each of three years are averaged and reported for the periods of 1990-1992, 1993-1995, and 1996-1998. |
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Age adjusted rates, such as for cancer incidences in this study, allow a comparison of rates between communities with different age structures. |
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Cortland Counts: An Assessment of Health and Well Being in Cortland County NY The Seven Valleys Health Coalition, Inc. These five organizations make up the Cortland Community Assessment Team (CAT) Seven Valleys Health Coalition, Inc.
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