Week 8 - Introduction To Probability And Statistics Flashcards
What is probability?
The quality or fact of being probable
A strong likelihood or chance of something
Expressed mathematically as a value between 0 and 1.
What is subjective probability?
Personal belief in the chance of something occurring
Informal probability that has no mathematical formula
What is objective probability?
Probability derived from mathematical principles
Frequentist probabilities are the most common examples (how often an event occurs in the long run)
What is conditional probability
Probability of an event occurring given some other condition is true
Probability of rolling a FAIR coin and getting heads is .5.
Probability of rolling SNAKE EYES with a pair of FAIR dice is .028.
Measuring and summarisingdata
Im order to describe and analyse data we need to summarise it
-what location does the data cluster around? (Central tendency)
How spread out or distributed are the data around the central location (variability)
What is the types of data in statistics, categorical/ nominal?
is an arbitrary label (homeowner. Nonesmoker, male)
Label be represented with a name or a number
Nominal: vanilla, strawberry
Numerical: 1, 3 ,
What’s an ordinal scale?
Inherent order (ranks), discrete, some info about quantity. Steps may not be equal.
What an interval scale
Order + equal intervals Continuous Mathematical operations Does not have a TRUE zero 0 on the scale doesn’t mean the absence of the thing (0 degrees is not an absence of heat) (Eg 24 hour time)
What’s a ratio scale?
A scale of measurement. Has order, equal intervals and a true zero.
Physical quantities are ratio scale (mass, length, time etc)
What’s a discrete variable?
Specific values, typically whole numbers.
Categorical variables are discrete (male, female)
What’s a continuous variable?
Unlimited resolution between minimum and maximum
Continuous variables can be converted to discrete variables (but not vice versa) Eg 0ml = none, 750ml = some 3750= too much
A construct can be continuous, but the method of quantifying it may be discrete.
What are descriptive statistics
Can describe or summarise a set of data (scores)
Primary uses of descriptive statistics
- to describe a central tendency
- to describe variability (spread)
What is central tendency?
Observations cluster around a fixed point.
What does it mean when data is Bimodal or multimodal?
Bimodal is where there’s two modes
Multimodal > two modal values
Is the median robust to outliers?
Yes, because it’s the middle value so outliers don’t affect it.
If there’s an even number of scores it’s the average of the two middle scores.
