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Probability- a fraction or a proportion of all the possible outcomes -…
Probability- a fraction or a proportion of all the possible outcomes
Random sampling
requires each individual in the population has an equal chance of being selected
if more than one individcual is being selected, the probailities must stay constant from one selection to the next
sample is called a simple random sample
independent random sampling- simply a random sample
Sampling with replacement- return each individual to the population before you make the next selection
random sampling with replacement-requires equal chance of selection and constant probabilities
Probability and Frequency Distributions
possible to represent probabilities as proportions of the graph
Probability and the Normal Distributions
find proportions/probabilities for specific z-Score values and locations that correspond to specific proportions
unit normal table- lists proportions of the normal distribution for a full range of possible z-score values
graph-
body
- larger part of the distribution,
tail
always the smaller section
proportions on the right-hand side are exactly the same the proportions on the left-hand side
proportions will always be positive
Probabilities, Proportions and z-Scores- z-Scores used to find corresponding proportions, find a specific z-Score from the proportions
most cases it is necessary to find probabilities for specific X values
Percentile rank- the percentage of individuals in the distribution with scores at or below that particular score
Percentile- particular score associated with a percentile rank
Finding Percentiles- given a percentage (a percentile rank) and must find the corresponding X value (the percentile)
Quartiles and Interquartile range- population form a normal distribution there is a simple method to compete the interquartile range from the unit normal table