Lecture 1
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What’s a descriptive statistic?
Numbers that describe a data set
what are the 3 categories of measure that makes up descriptive statistic?
1.) measures of central tendency 2.)measures of variability/spread 3.) Frequency distribution
Inferential statistic
method to make conclusions about a population using a sample
what is statistical bias?
Its when the statistic doesn’t accurately represent the population
Accuracy
is how well the the sample represents the population
Precision
is how close the samples/measurements were to each other
Define Histogram
a graph that shows the distribution of numerical data using bars
what are some things about a histogram sample that you couldn’t learn from the samples mean?
-distribution shape - presence of outliers - potential clusters
what happens to the difference between the mean of a sample and the mean of the population as size of the sample increase?
As the sample size increases it gets closer to the population size; meaning the difference between the mean sample and mean population size gets smaller.
Types of variables
qualitative (categorical) and quantitative (numerical)
Qualitative (categorical)
1.) nominal variables- categorical variable that describes a name, label, or category without a natural order 2.) Ordinal variable- a categorical variable where the categories have a natural order or ranking
quantitative (numerical)
Continuous variables- a variable that can take on an infinite number of values within a given range
define which variable is country of origin
nominal
define which variable is % of a population with a particular disease
continuous
define which variable is Rate of breathing, recorded as low, medium, or high
Ordinal
define which variable is Squirrel mass measured in grams
continuous
define which variable is whether a person is sick with a disease recorded as yes or no
nominal