CS235 Lecture Notes - Lecture 6: Bar Chart, Statistical Inference, Squared Deviations From The Mean
● Google employee august 2017 said because female brains are different they are not
good at engineering
● Statistical Analysis: the science of describing and reasoning from numerical data
○ Descriptive statistics
○ Inferential statistics
Visual Representations of Variables
● Data matrix
● Categorical variables
○ Pie charts - can immediately grasp numbers
○ Bar graphs - shows exact numbers in each category
● Continuous variables
○ Histogram - looks like bar chart but bars are touching
○ Scatter plot - used to compare variables (correlational)
Frequency Table
● List of all possible variables together with number of observations for each variable
Numerical Representations of Variables
● Measures of central tendency: statistical measures that reduce the dataset to a single
score that best characterizes the entire sample
○ Permit you to estimate what most of the sample loots like (eg avg exam score)
○ Measures:
■ Mode: most frequent score → nominal
■ Median: midpoint score - value that divides the distribution in half when
observations are ordered in terms of size
find more resources at oneclass.com
find more resources at oneclass.com
■ Mean: the sum of all scores divided by the number of scores (arithmetic
average) → the mean is the balance point of distribution
○ In a normally shaped distribution, the mean, median, and mode are the same
(bell-shaped curve)
○ In a skewed distribution, the mean is pulled toward the tail
Positive on top negative on bottom
○ Use mean when:
■ Interval or ratio data
■ The distribution is normally shaped
■ No missing data
■ Close-ended distribution
○ Use median when:
■ Ordinal data
■ The distribution is skewed, or have extreme scores (outliers)
■ Missing data
■ Open-ended distribution
● Measures of Dispersion
○ Range
■ Distance from the lowest to the highest score
○ Variance
■ Average of squared deviations from the same mean
■ Indicates variability about the mean
○ Standard deviation
find more resources at oneclass.com
find more resources at oneclass.com
■ Square root of variance
■ Indicates variability about the mean
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Google employee august 2017 said because female brains are different they are not good at engineering. Statistical analysis: the science of describing and reasoning from numerical data. Pie charts - can immediately grasp numbers. Bar graphs - shows exact numbers in each category. Histogram - looks like bar chart but bars are touching. Scatter plot - used to compare variables (correlational) List of all possible variables together with number of observations for each variable. Measures of central tendency: statistical measures that reduce the dataset to a single score that best characterizes the entire sample. Permit you to estimate what most of the sample loots like (eg avg exam score) Median: midpoint score - value that divides the distribution in half when observations are ordered in terms of size. Mean: the sum of all scores divided by the number of scores (arithmetic average) the mean is the balance point of distribution.
