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Statistics
Quiz 1 Terms
18
Mathematics
Undergraduate 2
02/18/2008

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Term
Population
Definition
the collection of items we want to better understand, and which we wan to draw a conclusion
Term
Parameters
Definition
summary calculations of the entire population set of data
Term
Sample
Definition
a portion of the population
Term
Statistic
Definition
a variable, since the value it takes on will depend on the sampling chance of which items are chosen for the sample.
Term
Sampling Error
Definition
the extent to which a sample statistic mis-estimates a population perameter, due only to "luck of the draw" (the random chance of sample selection). error caused by taking a sample that does not accurately portray the population as a whole
Term
Non-sampling Error
Definition
Actual human errors, encompassing all sources other than random sampling chance, that lead a statistic to mis-estimate the corresponding population perameter. i.e. innaccurate measurements, ambiguous terms, falsified responses, non-responses, lost data, not using genuine random selection from the population, computational errors
Term
Nominal Scale
Definition
serves only to distinguish one outcome from another (we can only tabulate "how many" fall in each catagory) Ex. color of shirt, brand of car
Term
Ordinal Scale
Definition
also conveys meaningful "rank order" (we not only tabulate frequencies, but also find percentiles) Ex. top 20 college football rankings, Consumer Reports product ratings
Term
Interval Scale
Definition
also allows us to interpret differences along the scale, i.e., a particular difference has the same meaning anywhere along the scale (we can tabulate frequencies, find percentiles, find a mean) Ex. # of children you have, current credit card balance
Term
Simple Random Sampling
Definition

a method of selecting a sample such that:

1) every item in the population has the same chance of being selected

2) every combination of items from the population has the same chance of being selected 

Term
Sampling Frame
Definition
The list/collection of items from which the sample is actualy chosen; i.e. the collection of items that could possibly appear in the sample.
Term
Quartiles
Definition
values representing the amount of data that lies beneath 25%, 50% and 75% of a sampled population (1st, 2nd, 3rd quartile, respectively) These numbers are medians within the data, therefore the 2nd quartile may represent the point in the data at which ten numbers lie above and below that point in the set
Term
Outlier
Definition
A data point which is rather far removed from the bulk of the rest of the data.
Term
Sample Mean
Definition
takes the numeric value of every data point into consideration; hence can be inluenced by extremes
Term
Median
Definition
the middle data item's value, after the items are put in increasing or decreasing order
Term
Standard Deviation
Definition
the square root of the variance; hence will always be in the original units of the data measurements
Term
Statistically Independent Variables
Definition
pattern in which outcomes for one variable is the same at every level of the other variable
Term
Statistically Related Variables
Definition
statistical relationship in which values have comparative probability patterns (not necessarily one variable "affecting" the other for a statistical relationship to exist)
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