Research

# Descriptive Statistics

Most of the research we are interested in as midwives is inferential – meaning we draw conclusions about a group of people based on the results.  However, descriptive statistics are still very helpful.

Descriptive statistics help us organize and summarize information.  For example, the number of births attended by midwives is a descriptive statistic. We can break down the data by country or state/province and see differences between groups. In experiments, the descriptive statistics help us ensure the two study groups are similar.

In healthcare, statistics isn’t useful without epidemiology.  Epidemiology is the study of patterns of illness and conditions. We use epidemiology to determine the causes of conditions, the effects of exposures and treatments and the patterns of spread for health issues.

In epidemiology, there are two terms to be familiar with for descriptive statistics:  incidence and prevalence. Let’s review these first with a non-health outcome – the number of midwives.

Incidence is a measure of new cases of something.  For example, according to the American Midwifery Certification Board, the incidence of first time candidates for the midwifery certification exam has increased from 297 in 2005 to 542 in 2013. This is the number of new midwives each year.

Prevalence is a measure of the total number of cases of something, this means the total pre-existing and all new cases. For example, according to the North American Registry of Midwives , the prevalence of certified professional midwives had increased from 624 in 2000 to 1828 in 2010.  This is the total number of midwives, both new and existing.

## Literature Example

Take a look at this article: Prevalence of Hepatitis B Virus Seromarkers in Young Adults Vaccinated at Birth; Impact on the Epidemiology of Hepatitis B Infection in Iran

In this study, the researches wanted to see if the infant immunization schedule for Hep B was successful at reducing infection rates.  To do this, the researchers tested a group of young adults to see what types of Hep B antibodies they had (from vaccination, from cleared infection or from chronic infection).  This means the researchers were looking at prevalence, or the total number of people who test positive for each particular type of antibody.

## Birth Worker Survey

The Birth Worker Survey  allows us to gather some descriptive statistics about the services offered by the readers of the Birthing Naturally website. Remember, our total was 31 responses. Here are descriptive statistics for the most commonly reported services.

Provide Midwifery Services: n= 6 (19%)

Provide Doula Services: n=24 (77%)

Provide Childbirth Education Services: n=16 (52%)

Provide Breastfeeding Education: n=15 (48%)

Provide Herb or Essential Oil Blending: n=5 (16%)

Provide Labor Photography: n=5 (16%)

Provide Placental Preservation: n=4 (13%)

#### Coming Up

In the next post, we’ll talk about some common problems with presenting data.