Statistical Measures
Frequency Distributions
- When we collect data about disease cases, we must put them in some kind of order. The most basic way to do this is to organize a “line listing”. Example: http://www.dhss.mo.gov/CDManual/CDsec30.pdf (scroll down to page 77).
- A line listing is actually a simple data base, in which each row represents a case of the disease we are investigating. Each column contains information about one characteristic, called a “variable.”
- Look at the data in Table 1
Table 1
Neonatal Listeriosis, General Hospital A, Costa Rica, 1989
| ID |
Sex |
Culture
Date |
Symptom
Date |
DOB |
Delivery Type |
Delivery Site |
Outcome |
Admitting
Symptoms |
| CS |
F |
6/2 |
6/2 |
6/2 |
Vaginal |
Del Rm |
Lived |
Dyspnea |
| CT |
M |
6/8 |
6/8 |
6/2 |
C-section |
Oper Rm |
Lived |
Fever |
| WG |
F |
6/15 |
6/15 |
6/8 |
Vaginal |
Emer Rm |
Died |
Dyspnea |
| PA |
F |
6/15 |
6/12 |
6/8 |
Vaginal |
Del Rm |
Lived |
Fever |
| SA |
F |
6/15 |
6/15 |
6/11 |
C-section |
Oper Rm |
Lived |
Pneumonia |
| HP |
F |
6/22 |
6/20 |
6/14 |
C-section |
Oper Rm |
Lived |
Fever |
| SS |
M |
6/22 |
6/21 |
6/14 |
Vaginal |
Del Rm |
Lived |
Fever |
| JB |
F |
6/22 |
6/18 |
6/15 |
C-section |
Oper Rm |
Lived |
Fever |
| BS |
M |
6/22 |
6/20 |
6/15 |
C-section |
Oper Rm |
Lived |
Pneumonia |
| JG |
M |
6/23 |
6/19 |
6/16 |
Forceps |
Del Rm |
Lived |
Fever |
| NC |
M |
7/21 |
7/21 |
7/21 |
Vaginal |
Del Rm |
Died |
Dyspnea |
Abbreviations:
Vaginal = vaginal delivery
Del Rm = delivery room
Oper Rm = operating room
Emer Rm = emergency room
- How many of the cases were male? We can easily pick out that information because there are only a few cases.
- But with a larger database, we cannot get that information at a glance. We must summarize variables into tables called “frequency distributions.”
Print this table - you will use it as you progress through the module.
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