math Flashcards
what are descriptive statistics
used to describe and organize data
what are inferential statistics
used to take data from samples and make
generalizations about a population
probability is a proportion always between what?
0 and 1
probabiity can be expressed as which of three?
proportion, fraction, or percentage
what does p = 0 mean?
the event will never occur
what does p =1 mean?
the event will always occur
probability is always what?
positive
what is a sample space?
contains all possible outcomes
- ex: 6 possible outcomes for a 6 sided die, so sample space is 6
what is an event
a particular outcome
- ex: rolling a 1 on a die
what is a complement of an event
all outcomes in the sample space not contained in the event
- ex: if you flip a heads, the complement is a tails
the probability of an event and the probability of a complement of the event is always equal what?
1
what is the probability formula?
of event outcomes /total # of possible outcomes
what is marginal (basic) probability
simple probability of an event that is not dependent on other event
what is joint probability?
the probability of two or more events occurring together
what is conditional probability?
the probability of an event given that another event occured
how do you find conditional proability?
find the joint probability, then divide it by p (A)
what are the parameters of a normal distribution?
the mean = median = mode
what is a normal distribution
a systematic distribution
what happens if you change the mean in a normal distribution?
data shifts left to right
what happens if you change the standard deviation in a normal distribution?
the spread of the data changes
the shape of the distribution can also be described by what?
the proportions of an area contained in each section of the distribution
the area under the curve is equal to what?
1
how do you find joint probability?
multiply two independent probabilities together
what is the chi square goodness of fit test used for?
categorical variables (ex: high vs. low perfectionism)
what are raw scores
original, unchanged scores
what are z-scores
establishes a relationship between the
raw score, the mean, and the standard deviation
what does a + sign mean in a z-score
it is above the mean
what does a - sign mean in a z-score
it is below the mean
what does 0 mean in a z-score
the score is equal to the mean
z-scores are what?
comparable.
standardized distributions are used to what?
make comparsions across different scales.
what are the 3 properiteis of a z distribution
- shape of distribution is the same
- mean is always equal to 0
- standard deviations is always equal to 1
