Introduction to Biostats (Lecture 2) Flashcards
What is nominal data?
- data can be placed into specific categories when order does not matter
- only a few values exist
- mutually exclusive
- “yes or no” - event either occurred or it did not occur
What is the difference between nominal and ordinal data?
ordinal data - has narrowly defined categories with few possible values in which the ranking-order matters
nominal data - data placed in specific categories when order does not matter
What kind of data would “male vs. female” be?
nominal data
Name type of data for: patient died or did not die
nominal data
Type of data used for: RASS Scale in ICU Sedation
Ordinal
What are the two types of discrete/non-parametric data?
- nominal
- ordinal
Nominal and ordinal data are types of ________ data, which is a type of ____ data
discrete/non-parametric data; qualitative data
Characteristics of discrete/non-parametric data:
- “categorical” variables
- usually have a few possible values
- can be counted but limited mathematical manipulation
scales, counts, and dichotomous outcomes (I.e., mortality) are examples of _______
discrete (non-parametric) data
What are the two types of continuous/parametric data?
- interval
- ratio
Characteristics of continuous/parametric data:
- May have an infinite number of values
- exist on some defined scale
- More mathematical manipulation possible
Weight, temperature, and age are examples of _____
continuous/parametric data
which type of data lacks a defined and meaningful zero point?
interval data
What is the difference between interval and ratio data?
interval data lacks a defined and meaningful zero point, whereas ratio data has a meaningful minimum or zero on the scale
- also can have a negative value for interval data (I.e., temperature), but cannot have a negative value in ratio data (I.e. weight, drug concentration, heart rate, blood pressure)
what is absolute zero?
non-existent measure at zero (can have in ratio data)
Type of data for: Celcius or Fahrenheit temperature (degrees)
interval
data where measurements are on a defined scale and scale of ranked differences is meaningful
interval and ratio data
type of data that can be compared
interval and ratio
weight, drug concentration, heart rate, and blood pressure are examples of what type of data?
ratio data
List and describe the 3 measures of central tendency:
- mean - the average of all values
- median - value in the middle of numerical order
- mode - value that appears most often
Which measure of central tendency is best when describing interval and ratio data?
mean
Which central tendency is best when outliers are present?
median
Which central tendency is best for non-numerical qualities?
mode
What are the 4 measures of distribution/spread?
- range
- interquartile range
- variance
- standard deviation
What is the purpose of measures of spread/distribution?
they are used to describe how data are spread to provide information about the variability in the distribution
the difference between the lowest and highest value in the data is _________
range
What is interquartile range?
the difference between the 25th and 75th percentile (median is the 50th percentile)
What is variance?
How far the values of a variable lie from the mean