EXAM 1 Flashcards
(38 cards)
empirical rule
approximately: 68% falls within one standard deviation 95% falls within two standard deviations 99.7% falls within three standard deviations
25th percentile
lower quartile 25% fall below
mean
the average the sum of all measurements divided by the number of measurements
random variable
a variable taht assigns a number to every outcome of an experiment
Systematic random sampling
systematically selecting every kth experimental unit from a list of all experimental units
sample variance
the sum of the squared deviations from the mean divided by (n-1) s
population
a set of units we are studying
variable
characteristic or property of an individual experimental unit
observational study
survey the researcher observes experimental units in their natural setting and record variables of interest
Binomial
results from experiments with two outcomes.
n: The number of times the experiment happens.
p: The probability of one specific outcome. You must have a fixed number of trials.
Each trial is an independent event. “Independent” means that every time you repeat the trial (i.e. tossing that coin), it’s a fresh new trial and nothing you do has an effect on each coin toss.
There are only two outcomes. In other words, if you can phrase the experiment as a yes or no answer, then it can be a binomial experiment: Will I get a heads? Can someone find a parking space in the city? Do eggs hard boil in ten minutes?
continuous
the variable can assign any value in an interval of values ex. heights of students ex. length of time to check out at lowes
published source
data set of interest has already been collected and is available in a published source like a book newspaper or journal
descriptive statistics
utilizes numerical and graphical methods to explore data (look for patterns, summarize, etc.)
measures of relative standing
descriptive measures of the relationship of a measurement to the rest of the data percentiles z-scores
modified empirical rule
expect most data to fall within 2 standard deviations of the mean approx 60-90% fall between 1 standard deviation approx 90-100% fall between 2 standard deviations approx 100% fall between 3 standard deviation
methods of collecting data
published source designed experiment observational study
quantitative data
measurements that are recorded on a naturally occurring numerical scale dot plots, stem and leaf, histograms,
Statistics
the science of data. involves collecting, classifying, summarizing, organizing, and interpreting numerical and categorical information
Chebyshev’s rule
any data set regardless of the shape of the frequency distribution of the data: will have no useful information if within 1 S.D. 75% will fall between two standard deviations 89% will fall between three standard deviations
graphing methods for describing quantitative data
data recorded on meaningful numerical scale dot plot steam and leaf display histograms
Cluster Sampling
Sample natural groupings(clusters) of experimental units first and the collect data from all experimental units within each cluster
stratified random sampling
experimental units associated with the population can be separated into groups of strata (units) characteristics of the experimental units are more similar within strata than across strata
qualitative data
data collection method where the researcher has full control over the characteristics of the experimental units sampled
z-scores
number of standard deviation an observation falls from the mean and which direction (x-mean)/standard deviation gives you an idea of how far from the mean a data point is. But more technically it’s a measure of how many standard deviations below or above the population mean a raw score is.
