Regression Analysis

Introduction

Gunshot wounds; bullet caliber is increasing, a look of this increase from years 1998-2003. This data is derived from the use of larger caliber firearms in accidents, homicides and suicides. Data was collected from the measurements of bullets removed from trauma patients then submitted to a surgical pathology laboratory. This data was collected from the years of 1998 to 2002 with patient medical record number and the year obtained. Approximately 78 percent of all bullets were intact and sufficient for use in the study. Bullet fragments and pellets were excluded.

"Among gun deaths in the United States, a very small fraction of all crimes are attributed to firearm accidents, firearm injuries of undetermined intent and legal intervention involving firearms. These deaths amount to 4.4 percent of the total numbers of gun deaths (25,663) in the United States during the most recent year (2000) such data are available. Of the remaining 95.6 percent of gun deaths, homicide accounted for 37.7 percent and suicide for 57.9 percent. This apparent increase in suicide by gun contrasts similar data from 1985, when homicide (44.1%) more closely paralleled suicide (51.8%) by gun." (Caruso, RP, Swan, KG, 2003)

The article in this paper suggest that "mortality does not increase and even seemingly decreases because care for the trauma victims has become so increasingly innovative, efficient, and comprehensive that the trauma victims, including patients injured by missiles from guns, who would have died from their wounds in the past are now survivors. " (Caruso, RP, Swan, KG, 2003)

Caliber is defined as the diameter of a missile or of the barrel for the weapon (bore) through which the bullet passes.

Caliber is expressed in hundredths (two digits) or thousandths (three digits) of an inch. Preceding "caliber" with a decimal point is actually incorrect because the decimal point is redundant. Caliber implies hundredths or thousandths of an inch. Caliber can also be expressed in millimeters, divided by 25.4 equals the caliber. Thus, 9 mm ч 25.4 = 35 caliber. Conversely, caliber times 25.4 equals diameter of bullet in millimeters. Thus, a 45 caliber bullet will measure 11.4 mm in diameter as will the bore or internal diameter of the barrel of the gun designed to fire the round or the cartridge containing the bullet. Bullet, plus powder, primer, casing, and so forth, constitutes the cartridge or round. Bullet, strictly speaking, consists only of the missile leaving the end of the weapons' barrel." (Caruso, RP, Swan, KG, 2003)

"Bullets submitted to surgical pathology during the years of 1998 through 2002 were measured with a millimeter rule to determine caliber or transverse diameter. Bullet calibers were expressed in terms of mean plus or minus standard error. Mortality figures were derived from analysis of medical records concerning the outcomes of all victims of gunshot wounds treated at the trauma center in Newark, New Jersey, during the years studied and expressed as percentages." (SafetyLit, 2004 p 42)

Due to the vast amounts of data in the aforementioned article, Team C has chosen to perform a regression analysis based on two data sets from within the article. Regression analysis allows us to develop a mathematical equation to enable us to "estimate the value of one variable based on the variable of another." (Regression Analysis in Research, p.139) In regression analysis, one variable is always dependent on another, called the independent variable.

The data sets tested are the mean caliber of bullets used, along with the mortality percentage associated with gunshot wounds through the years 1998 to 2002.

The mean caliber of bullets is the independent variable, as the percentage of gunshot mortality is dependent on this data, thus making it the dependent variable.