Evidence-Based Practice for Nurses

Secular

» Trends over years

Cyclical

» Seasonal trends

Short-term changes

» Epidemics

BOX 8-2

Examples of Descriptive

Characteristics by Time

relate to infectious diseases. A common infectious disease with a seasonal

trend is influenza. The CDC trends positive influenza test results reported each

week. Figure 8-3 shows that during the 2016–2017 influenza season, positive

influenza test results peaked during the 8th week of 2017 (CDC, 2017).

<20%

20%–<25%

25%–<30%

30%–<35%

≥35%

AK

HI

GU

PR

WA

ID

MT

WY

CO

ND

MN

IA

MO

AR

LA

MS AL GA

FL

NJ

DE

MD

SC

TN NC

KY

IL IN

WI

MI

OH

PA

WVVA

NY

ME

VT

NHMA

SD CT RI

NE

KS

OK

TX

AZ NM

NV UT

OR

CA DC

Prevalence estimates reflect BRFSS methodological changes started in 2011. These estimates should not be

compared to prevalence estimates before 2011.

FIGURE 8-2 Prevalence of Self-Reported Obesity Among U.S. Adults

Reproduced from Centers for Disease Control and Prevention. (2017). Overweight & obesity: Adult

obesity prevalence maps. Retrieved from https://www.cdc.gov/obesity/data/prevalence-maps.html

202 CHAPTER 8 Epidemiologic Designs: Using Data to Understand Populations