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Chapter 2

Sociology 2205A/B Chapter Notes - Chapter 2: Interval Ratio, Mortality Rate, Frequency Distribution

Course Code
SOC 2205A/B
William Marshall

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1. Chapter 2: Basic Descriptive Statistics
2.1: Percentages and Proportions
Percentages and proportions allow for standardizing raw data and making it more
understandable and relatable
Percentages are to the base 100 f = frequency, or the number of cases in any category
n = the number of cases in all categories
Proportions are to the base 1.00
Formula 2.1: proportion (p) = f/n
Formula 2.2: percentage (%) = (f/n) x 100
When working with small cases (fewer than 20) it is usually preferable to report in
actual frquencies
Always report the number of observations along with proportions and percentages
a. Ex. 2/3 people smoke, while 25 people were tested
Percentages and proportions can be calculated for variables at the ordinal and nominal
levels of measurement
a. Ex. 43% of the sample is female (only expressing the relative size, female of the
variable, gender)
2.2: Ratios and Rates
Ratios and rates provide some additional ways of summarizing results simply and clearly
Useful for comparing categories of a variable in terms of relative frequency
Ratios express the relative size of the categories/exactly how much one category
outnumbers the other
Formula 2.3: Ratio = f1/f2 f1 = the number of cases in the first category
f2 = the number of cases in the second category
Provide another way of summarizing the distribution of a single variable
Defined as the number of actual occurrences of some phenomenon divided by the
number of possible occurrences per some unit in time
Usually multiplied by some unit of 10 to get rid of decimal points
Ex. The crude death rate for a population is defined as the number of deaths in that
population (actual occurrences) divided by the number of people in the population (possible
occurrences) per year. This quantity is then multiplied by 1000
Crude death rate = number of deaths (actual occurrence) / Total Population (possible occurrence)
x 1000
Crude death rate =
2.3: Frequency Distributions Introduction
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