# Shared Flashcard Set

## Details

Statistics Exam 1
Ch. 1, 2, 4.1-4.3
45
Mathematics
09/22/2011

Term
 Descriptive Statistics
Definition
 The collection, presentation, and description of sample data
Term
 Inferential Statistics
Definition
 Interpreting the values that result from the descriptive techniques and making decisions and drawing conclusions about the population.
Term
 Statistics
Definition
 The science of collecting, describing, and interpreting data
Term
 Population
Definition
 A collection, or set, of individuals or objects or events whose properties are to be analyzed.
Term
 Finite Population
Definition
 When the membership of the population can be physically listed
Term
 Finite Population
Definition
 When the membership of the population is unlimited
Term
 Sample
Definition
 A subset of a population
Term
 Variable (or Response Variable)
Definition
 A characteristic of interest about each individual element of a population or sample
Term
 Data (Singular)
Definition
 The value of the variable associated with one element of a population or sample. This value may be a word, a number, or a symbol.   Ex. Bill entered college at age "23"
Term
 Data (Plural)
Definition
 The set of values collected for the variable from each of the elements that belong to the sample.
Term
 Experiment
Definition
 A planned activity whose results yield a set of data
Term
 Parameter
Definition
 A numerical value summarizing all the data of an entire population
Term
 Statistic
Definition
 A numerical value summarizing the sample data
Term
 Qualitative, or Attribute, or Categorical Variable
Definition
 A variable that describes or categorizes an element of a population
Term
 Quantitative, or Numerical Variable
Definition
 A variable that quantifies an element of a population
Term
 Nominal Variable
Definition
 A qualitative variable that categorizes (or describes, or names) an element of a population. Not only are arithmetic operations not meaningful for data that result from a nominal variable, but also an order cannot be assigned to the categories
Term
 Ordinal Variable
Definition
 A qualitative variable that incorporates an ordered position, or ranking
Term
 Discrete Variable
Definition
 A quantitative variable that can assume a countable number of values. Intuitively, the discrete variable can assume the values corresponding to isolated points along a line interval. That is, there is a gap between any two values   Ex. counting
Term
 Continuous Variable
Definition
 A quantitative variable that can assume an uncountable number of values. Intuitively, the continuous variable can assume any value along a line interval, including every possible value between any two values   Ex. measuring
Term
 Measures of Central Tendency
Definition
 Mode, mean, median, midrange
Term
 Histogram
Definition
 A histogram is a frequency graph that depicts the frequency distribution of a quantitative variable
Term
 Weighted Average
Definition
 Use when one value is "worth" less (x2 in your sample than normal society)
Term
 Midpoint
Definition
 (x-min + x-max) / 2Midrange – middle of the data set
Term
 Mean
Definition
 average
Term
 Median
Definition
 the middle number (half the area of the curve) when data are ranked according to sizeAs soon as there is a big difference between the mean and median, you know you have skew in your data (either left or right)
Term
 Mode
Definition
 which value occurred the most times
Term
 Range
Definition
 H - L
Term
 z-score (standard score)
Definition
 You can make more meaningful comparison between two x-values that came from separate populations. An x's z-score defines how many standard deviations from the mean the x-value is. z = (value - mean) / st. dev.
Term
 The Empirical Rule
Definition
 68.3% of observations will lie within 1 standard deviation from the mean (~15.6% in each tail)95.4% of observations will lie within 2 standard deviations from the mean (~2.3% in each tail)99.7% of observations will lie within 3 standard deviations from the mean (~0.15% in each tail)
Term
 Empirical Probability
Definition
 probability of A = number of time A occurred / number of trials
Term
 Theoretical Probability
Definition
 probability of A = number of times A occurs in a sample space / number of elements in sample space
Term
 Relative Frequency
Definition
 found by dividing the class frequency by the total number of observations
Term
 Law of Large Numbers
Definition
 As the number of trials goes up, the observed relative frequency (empirical probability) will tend to approach the theoretical probabiltiy
Term
 Sample Space
Definition
 The list of all possible outcomes of the experiement
Term
 Marginal Probability
Definition
 P(single event)
Term
 Joint Probability
Definition
 P(two events)
Term
 Conditional Probability
Definition
 P(A|B) = P(A n B) / P(B)n = intersection, include all events that are in both A and B
Term
 Stochastic Process
Definition
 Probability ModelsStochastic process - random. Sometimes there's predictability about the pattern, not the variable.
Term
 Bernoulli Process
Definition
 a random process with only two outcomes: "success" x=1 or "failure" x=0----A Bernoulli process gives rise to the binomial distribution.What is the random variable that has a binomial distribution? x = number of successful trialsWhat is the range of x? n - 0
Term
 Probability
Definition
 when we make inferences about a population whose elements are all known, they are not inferences - we know all the possibilities
Term
 Independent vs. Dependent Events
Definition
 If you compare marginal and conditional probability, you can see that you have independent or related events. If the numbers are the same, it means that they have nothing to do with each other. If the numbers are radically different, then you have related events.
Term
 3!
Definition
 1x2x3
Term
 Uniform Distribution
Definition
 every value appears with equal frequency
Term
 Percentailes
Definition
 Values of the variable that divide s aset of ranked data into 100 equal subsets; each set of data has 99 percentiles. The kth percentile, Psubk, is a value such that at most k% of the data are smaller in value than Psubk, and at most (100-k)% of the data are larger
Term
 Distribution
Definition
 The pattern of variability displayed by the data of a variable. The distribution displays the frequency of each value of the variable
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