# AP STAT REVIEW Flashcards

Terms Definitions
 1/p Geometric mean Bimodal Having two modes Unimodal Having one mode Parameter Measure of a population Blocking Experimentation where groups of subjects are divided into "blocks" and tested upon within each of these blocks Multimodal Having more than two modes Random variable Represents the different numbers associated with potential outcomes of certain scenarios Continuous Random variables that can assume values throughout the whole line interval Histogram Graphical display where relative area corresponds to relative frequency Quantitative displays Term which includes histograms, cumulative frequency plots (ogives), and stemplots Categorical Variable All variables that name categories Median (and IQR) Resistant to extreme values (outliers) True Natural variation in outcomes can be reduced by using more subjects - True or False? Experimental units Objects which an experiment is conducted upon; called "subjects" when they are human Confounded When there is uncertainty with regard to which variable is causing an effect Conditional probability Probability of an event happening given that another event has occurred Double-blinding When both the subjects nor those evaluating their responses know which treatment the subject has received t-distribution We use this distribution because of the increase in the variability of the test statistic due to the estimation of the population standard deviation Contingency Table Displays counts (%) of individuals falling into categories on two or more variables Multistage sampling Type of sampling which is a combination of two or more types of sampling [(s^2)/n + (s^2)/n]^0.5 Drawing one standard deviation value from standard deviations of two independent samples Relative frequency Number of times an occurrence happened divided by total number of trials Placebo effect Psychological response to any kind of perceived treatment, even if treatment is simply a placebo Clusters, Outliers Two major things to note when analyzing scatterplots Deciles Values that lie up 1/10th and 9/10th of the way up a list; have percentile ranks of 10% and 90% Discrete Random variables that can only be a counted number Stem-and-Leaf Display Shows quantitative data values in a way that sketches the distribution of the data Skewed When a graph is not symmetric, you look at which tail stretches out further Randomized paired comparison design Experimentation in which subjects are paired together and which subjects receiving which treatment is randomized False A r-value of 0 indicates there is no relationship between two variables - True or False? Outliers on x-axis Which type of outliers are most influential on the LSRL? Controlled random experiment What can indicate cause & effect relationships? Frequency Table A table that lists categories in a categorical variable and gives counts of observations for each category (a) increase alpha, (b) increase sample size, (c) decrease variation (st. deviation, variance, etc.) Three ways to increase power df = n - 2 Degrees of freedom for Confidence Interval for population slope of LSRL Quantitative Variable A variable in which the numbers act as numerical values (a) 2 outcomes per event (b) independent observations (c) probability of success is constant (d) varying number of trials Factors of a geometric setting Simple random sample (SRS) Way of selecting a sample so that each subject has equal chance of being chosen and that every possible of any size has an equal chance of being chosen If the car speed was 0 MPH, we predict the mileage to be approximately 30 MPG. Interpret a y-intercept of 30 in the relationship of speed vs. mileage Simulation A pretend experiment bias systematically favors certain outcomes numerical each observation is a number null hypothesis hypothesis to be tested y hat variable representing the predicted value of the response variable 1st Quartile 25% of data lies below population (statistics) the entire aggregation of items from which samples can be drawn Probability that chance of an event occurring undercoverage some portion of the intended population is either unrepresented or under-represented Response Variable Measures an outcome of a study replication ensuring that there is an adequate number of observations on each experimental treatment Marginal Distribution In a contingency table, the distribution of either variable alone placebo something presented as a drug (or whatever you are trying to test in your experiment), but having no actual effect on the person. Sample The part of the population actually examined in order to gather information. mean of a density curve The balance point. factor a variable whose levels are controlled by the experimenter to discover its effects on the subjects Observational Study observes individuals but does not attempt to influence the response. No treatment!! correlated degree to which two variables are associated Sampling Studying a part in order to gain information about the whole Confounding When the levels of one factor are associated with the levels of another factor in such a way that their effects cannot be seperated. Control A sample that is treated like other experimental groups except that the independent variable is not applied to it stratified random sample first divide the population into groups of similar inviduals called strata voluntary rsponse bias when people can chose to responde independent events when the probability or occurence of one event has no effect on the other event Distribution a display of the data WITH LABELS!!! .They can be different shapes...(skewed left, symmetric, skewed right) standard deviation A measure of spread that describes an average distance from the mean. Slope B1 gives a vlue in y units per x linearity the notion that one event is a cause and the other is its effect; in behavior, the idea that one behavior is a stimulus and the other a response. Linear thinking is opposite of circular thinking, in which events are thought to be related in a series of interacting loops Control group a group in an experimental study that is not given any specific treatment dotplot a display for either kind of data that uses a dot to represent each individual in the data set Simpsons Paradox : the reversal of some apparent trend when data are further explored or when groups are combined. extraneous factor a variable that is not of interest in the current study but is thought to affect the response variable Voluntary Response Bias When we receive biased results due to the responses received prospective study a study where we collect data as it happens planning and conducting a study 1. understand the nature of the problem 2. decide what & how to measure 3. collect data 4. summarize & do preliminary analysis 5. do formal data analysis 6. interpret results Population Distribution of a Variable of Interest (or, more simply, The Population Distribution) The distribution of the variable of interest throughout a given population. Namely, each individual in a given population is measured or observed and the resulting distribution is simply called the population distribution.
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