# Shared Flashcard Set

## Details

Ch. 1-5
115
02/09/2009

Term
 What is Statistics?
Definition
 The art and science of collecting, analyzing, presenting, and interpreting data.  In business, it gives managers a better understanding of business enviroment, enabling them to make more informed and better desicions.
Term
 Data   Data Set
Definition
 The facts and figures that are collected, analyzed and summarized for presentation and interpretation.    all the data collected in particular study
Term
 Elements
Definition
 The entities of which data are collected
Term
 Variable
Definition
 AN attribute or characteristic of an entity
Term
 Observation
Definition
 The set of measurements for a particular element  # is equal to # of elements   The number of measurments obtained for each element is queal to the number of varibles.  total # of data items= # of observations multiplied by the # of variables.
Term
 What is the scale of measurement?
Definition
 determines the amount of information contained in the data and indicates the data summarization and statistical analysis that are more appropriate.  NominalOrdinalIntervalRatio
Term
 Nominal
Definition
 data are labels or names can be numeric or nonnumeric
Term
 Ordinal
Definition
 The data have the properties fo nomral data and cab be orderedin some meaningful way. RANKED Ex. Survey: Excellent, Good, Poor
Term
 Ratio
Definition
 The data have the properties of interval data and contain an absolute zero value resutling in meaningful ratios.   Ex. Distance, Height, Weight, and Time
Term
 Which Scales of Measurement describe Qualitative Data?
Definition
 Nominal and Ordinal
Term
 Which Scales of Measurement describe Quanitative Data?
Definition
 Interval and Ratio
Term
 What is Qualitative Data?
Definition
 use labels or names to describe an attribute of an element
Term
 Categorical Data can also be referred to as..
Definition
 Qualitative Data
Term
 What is Quantitative Data
Definition
 It indicates how much or how many it can be discrete or continuous.
Term
 Why does the Statistical Method used for summarizing data depend on whether the data is qualitiative or quantitative
Definition
 Qualitative variable is limited in terms of statistical analysis because its nominal. Its hard to do arthematic on the data. Quantitative variables you are able to find the mean, median, mode, etc. as well as add, divide, mulitply, etc.
Term
 What is cross-sectional data?
Definition
 Data that is collected at approximately the same time
Term
 What is time series data?
Definition
 Data that is collected over a period of time or series of time periods...  ex. Weather throughout the Year in San Diego
Term
 Statistical Studies are classified as either..
Definition
 Experimental or Observational
Term
 When a Statistical Study is Experimental.. the researchers...
Definition
 control one or more independent varible (IV) to measure their influence on a dependent variable(DV)
Term
 When a Statistical Study is Observational.. the researchers..
Definition
 make no attempt to control the independent variable.  ex. survey for a restruant.
Term
 What are descriptive statitistics?
Definition
 summaries of data that may be tabular, graphical, or numerical
Term
 What is the most common numerical descriptive statistic?
Definition
 average, or mean.
Term
 What is the population?
Definition
 The set of all elements of interest in a particular study.
Term
 What is a Sample?
Definition
 It is the subset of the population.
Term
 What is a census?
Definition
 the process of conducting a survey to collect data for the entire population.
Term
 What is the process of conducting a survery to collect data for a sample called?
Definition
 Sample Survey
Term
 What is Statistical Inference?
Definition
 The process of taking data from a sample and using it to make estimes and test hypotheses about the characteristics of a population.
Term
 What are some unethical behavior for statistical practice?
Definition
 improper samplinginappropriate analysis of the dataDevelopment of misleading graphsuse of inappropriate summary statisticsbiased interpreation of the statisical resultsmultiple tests until a desired result is obtained
Term
 you must always be ________ when conducting an experiment or you may have a bias on the interpretation of the statistical results.
Definition
 impartial
Term
 percent of statistics that are made up on the spot
Definition
 67
Term
 What are Sample Statistics?
Definition
 numerical measures computed from a sample (eg. the sample mean, and the sample standard deviation
Term
 What are the population parameters?
Definition
 Numerical measures computed from a population (eg. the population mean, and the population standard deviation)
Term
 What is the point estimate in Statistical Inference?
Definition
 The sample statistic used to estimate the corresponding population parameter (eg. the sample mean is often used as a point estimate of the population mean)
Term
 What is the Mean?
Definition
 arithmetic average or average value of a variable  ** Most important measure of location**  add up the numbers and divide by the total number of participants. The data can be skewed with an outlier.
Term
 The Sample Mean is the _________ of the population mean
Definition
 Point Estimator
Term
 What is the Median?
Definition
 The middle value when the data is sorted in ascending order.  To compute the median, sort the data in ascending order:if n is odd, the median is the middle numberif n is even, the median is the average of the two middle numbers
Term
 Which measure of location is resitant to outliers?
Definition
 median
Term
 What is Mode?
Definition
 The value occurs at the greatest frequency.   ** There is NO MODE if no number is repeated***There can also be MULTIPLE MODES**(ex. 1,2,2,3,3,5) mode- 2&3
Term
 If the bell curve is ________, the mean and median will equal eachother
Definition
 symmetrical
Term
 If the _______ and ________are equal to eachother, that does not mean that the _____________ is symmetrical.
Definition
 (1)mean (2)median (3)bellshape curve
Term
 Bimodal
Definition
 if a set of data has 2 modes
Term
 multimodal
Definition
 if a set of data has 3 or more modes
Term
 What measure of location used as the most important in qualitative data
Definition
 Mode  ex. distribution of soft drinks. Want to know which soft drink is purchased most frequently.. Coke Classic
Term
 What is a Percentile?
Definition
 the pth percentile is a value that at least p percent of the observations are ≤to this value and at least (1-p) percent of the observations are ≥ to this value  ex. 67 percentile67 percent fall below this percentile while 33 percent are above this percentile.
Term
 how do you calculate the pth percentile?
Definition
 1. sort data in ascending order (small to large)2. compute an index- i i= (p/100)n *p= percentile of interest, n=# of observations/times, i= the item which is in the P percetile 3. (a) if i is not an interger, round up.the next interger greater than i denotes the position of the pth percentile.  (b) if i is an interger, the pth percentile is the average of the values in positions i and i+1
Term
 The 50th percentile is also known as the...
Definition
 median
Term
 What are quartiles?
Definition
 Specific percentiles, seperated in 4. 25,50,75
Term
 What are the division points of Q1, Q2, and Q3?
Definition
 Q1= first quartile, or 25th percentile Q2= second quartile, or 50th percentile (median)Q3= third quartile, or 75th percentile
Term
 What are the measures of variabilty?
Definition
 range, interquartile range, variance, standard deviation, coeffecicent of variation (cv)
Term
 What is the simplist measure of variability?
Definition
 range
Term
 how do you calculate range?
Definition
 largest value- smallest value
Term
 How do you computer the Interquartile Range, and what is it?
Definition
 IQR=Q3-Q1 Its the range for the middle 50% of the data. It overcomes the dependency on extreme values
Term
 What is Variance?
Definition
 measure of variabiltiy that utizles all the data.  its the difference between the value of each observation (xi) and the mean
Term
 What is the difference between each observation(xi) and the mean called?
Definition
Term
 The __________ is useful in comparing the variabiltiy of two or more variables
Definition
 variability
Term
 For any data set, the sum of the deviations about the mean will...
Definition
 always be zero
Term
 The sample standard deviation is the ______________ of the population variance.
Definition
 point estimator
Term
 What is the Coefficient of Variation?
Definition
 its a relative measure of variability; it measures the standard deviation relative to the mean.
Term
 The coefficent of variation is a useful statistic for comparing the variabiltiy of variables that have...
Definition
 different standard deviations and different means
Term
 Use the _______ and the _________ together, we can learn about the relative location of observations in a data set.
Definition
 mean and standard deviation
Term
 When data is skewed, you want to use the
Definition
 median
Term
 The _________ is resitant to outliers.
Definition
 median
Term
 the _____________ represents a more accurate number of the population.
Definition
 median
Term
 What is a Z-Score?
Definition
 often reffered to as the standardized value. it is a number of standard deviations an observation is away from the mean. it tells you the location.
Term
 Z scores should normally be used only in ____________ distributions
Definition
 normal  exception: can sometimes be used in similar distributions
Term
 (1)If Z score is positive, its ______ the mean (2)If Z score is negative, its ______ the mean
Definition
 (1) above(2) below
Term
 What are the distributions within the empirical rule?
Definition
 µ±1σ(STD DEV)≈68%µ±2σ(STD DEV)≈95%µ±3σ(STD DEV)≈99.7%
Term
 you can use ___________ to identify outliers.
Definition
 Z-scores
Term
 a data value is an outlier if it is ________ from the mean.
Definition
 above ±3 STD DEV
Term
 What is in a 5 number summary?
Definition
 1. Smallest Value2. First Quartile (Q1)3. Median (Q2)4. Third Quartile (Q3)5. Largest Value
Term
 A _________________ is a graphical summary of data that is based on a five-number summary.
Definition
 box-plot
Term
 What is Covariance?
Definition
 it describes the linear association between two or more variables.
Term
 What is the correlation coefficient?
Definition
 The correlation tells us the relationship between the two variables. it further develops covariance.
Term
 If the Correlation Coefficient is _________, the variables go in the same direction.    / If the Correlation Coefficient is _____________, the variables go in the opposite direction.   \
Definition
 positive  negative
Term
 if the correlation coefficient is approx. 0, x and y are....
Definition
 not linearly related.
Term
 Weighted Mean
Definition
 the mean is comuted by giving each observation a weight that reflects its importance.
Term
 What is Variance?
Definition
 a measure of variability based on the squared deviation of the data values about the mean.
Term
 What is the experimental outcome when you...  Toss a CoinSelect a part for inspectionconduct a sales callroll a dieplay a football game
Definition
Term
 What is probability?
Definition
 its a numerical measure of the likelhood that an event will occur
Term
 Probability values are always assigned on a scale from _____to______
Definition
 0 to 1
Term
 A probability near zero indicates an event is ____________ to occur
Definition
 unlikely
Term
 A probability near 1 indicates an event is ________________ to occur
Definition
 almost certain
Term
 in probability, what is an experiment?
Definition
 its a process that generates well-defined outcomes
Term
 on any single repeitition of an experiment, how many possible experimental outcomes will occur?  (in reference to probability)
Definition
 one and only one.
Term
 what is the sample space for an experiment?
Definition
 the set of all experimental outcomes.
Term
 experimental outcomes are also called...
Definition
 sample points
Term
 What is the counting rule for Multiple- Step Experiements?
Definition
 if an experiment can be described as a sequence of k steps with n1 possibile outcomes on the first step, n2 possible outcomes on the second stpeh, and so on, then the total number of experimental outcomes is given by (n1)(n2)...(nk).  ex. tossing 2 coins. what are the possible outcomes?n1=2; n2=2, so (2)(2)=4.
Term
 In the Counting Rule for Combinations, order (does/doesnt) matter?
Definition
 doesnt
Term
 in a combination 0! = ?
Definition
 1
Term
 5! is equal to..
Definition
 (5)(4)(3)(2)(1)= 120
Term
 In the Counting Rule for Permutations, order (does/doesnt) matter?
Definition
 DOES
Term
 The three approaches most frequently used to assign probabilties are:
Definition
 1. Classical2. Relative Frequency3. subjective methods  top 2 are the best approaches*
Term
 The _____________method of assigning probabilities is appropriate when all the experimental outcomes are equally likely.
Definition
 classical
Term
 1 n is used in the ________method  n being the experimental outcomes
Definition
 classical
Term
 The ____________________method of assigning probabilites is appropriate when data are available to estimate the proportion of the time the experimental outcome will occur if the experiment is repeated a large number of times.
Definition
 relative frequency
Term
 The ______________method of assigning probabilties is most appropriate when one cannot realistically assume that the experimental outcomes are equally likely and when little relevant data are available.
Definition
 subjective method.   *its arbitrary, its a feeling, there isnt hard data, its pretty common espeically when data is hard to obtain.
Term
 For an experiment to be assigned probabilties it must:  (2 things)
Definition
 1. the outcome must be between 0 and 1.2. the sum of the probabilties for all the experimental outcomes must equal 1.
Term
 what is an event?  (probability, ch.4)
Definition
 is a collection of sample points or experimental outcomes.
Term
 What is the probability of an event?
Definition
 It is equal to the sum of the probabilities of the sample points in the event.
Term
 Given an event A, What is the complement A?
Definition
 its the event consisting of all sample points that are not in A. The completment of A is denoted by Ac
Term
 P(A)+ P(Ac)=
Definition
 1
Term
 The _________ of A and B is the event containing all sample points belonging to A or B or both. It is denoted by ________.
Definition
 union   A υ B
Term
 Given two events, A and B, the _____________ of A and B is the event containing the sample points belonging to both A and B.  Its denoted by ________
Definition
 intersection A ∩ B
Term
Definition
 it is used to compute the probability of the union of two events.  P(AUB)= P(A)+P(B)-P(A∩B)
Term
 What are Mutually Exclusive Events?
Definition
 Two events are said to be Mutually Exclusive if the events have no sample points in common.
Term
 What is the Addition Law for Mutually Exclusive Events?
Definition
 P(AUB)= P(A)+P(B)
Term
 P(A∩B)= 0 when A & B are ___________.
Definition
 mututally exclusive (disjoint)
Term
Definition
 The probability of A given B
Term
 What is Conditional Probability?
Definition
 The probabulity of an event given that another event already occurred.  The conditional probability of A given B is P(A|B)= P(A∩B)/P(B)
Term
 What is Joint Probability?
Definition
 THe probability of two events both occurring; that is, the probability of the intersection of two events.
Term
 What is Marginal Probability?
Definition
 The values in the margins of a joint probability table that provide the probabilities of each event separately.
Term
 What are independent events?
Definition
 two events A and B where P(A|B)=P(A)or P(B|A)=P(B);   that is, the events have no influence on each other.
Term
 What is the Multiplication Law?
Definition
 A probability law used to compute the probabilty of the intersection of two events.  For Dependent events: P(A∩B)= P(B)P(A|B) or  P(A∩B)= P(A)P(B|A). For Independent events:P(A∩B)= P(A)P(B)
Term
 Interval
Definition
 The data have the properties of ordinal data and equal distances on the scale represent equal distances being measured.*always numeric
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