AP Statistics - Chapter 4 Flashcards

5176096920	Population	The entire group of individuals about which we want information	0
5176096921	Sample	The part of the population from which we actually collect information. We use this info to draw conclusions about the entire population.	1
5176096922	Sample Survey	A survey which is carried out using a sampling method, i.e. in which a portion only, and not the whole population is surveyed.	2
5176096923	Convenience Sample	Choosing individuals who are easiest to reach...almost guaranteed to show bias.	3
5176096924	Bias	Using a method that will consistently overestimate or underestimate the value you want to know. This design of a statistical study systematically favors certain outcomes.	4
5176096925	Voluntary Response Sample	Consists of people who choose themselves by responding to a general appeal. Show bias because people with strong opnions are the most likely to respond.	5
5176096926	Random Sampling	Use of chance to select a sample. This is the central principle of statistical sampling.	6
5176096927	Simple Random Sample (SRS)	The simplest way to use chance to select a sample e.g. place names in a hat and draw names. Consists of size (n) of (n) individuals from the population chosen in such a way that every set of (n) individuals has an equal chance to be the sample actually selected.	7
5176096928	Table of Random Digits	A long string of the digits 0, 1,2,3,4,5,6,7,8,9 with the following properties: 1) Each entry in the table is equally likely to be any of the 10 digits 0 thru 9. 2) The entries are independent of each other..Knowledge of one part of the table gives no info about any other part.	8
5176096929	Stratified Random Sample	Classify the population into homogeneous groups and then choose a separate SRS in each group and combine to form a full sample.	9
5176096930	Cluster Sample	Classify the population into heterogeneous groups and then choose a SRS of some of of the groups, using every individual in the selected groups.	10
5176096931	Inference	The process of drawing conclusions about a population on the bais of sample data	11
5176096932	Margin of Error	An amount (usually small) that is allowed for in case of miscalculation or change of circumstances.	12
5176096933	Sampling Frame	List of individuals from which a sample is drawn.	13
5176096934	Undercoverage	Occurs when some groups in the population are left out of the process of choosing the sample.	14
5176096935	Nonresponse	Occurs when an idividual chosen for the sample can't be contacted or refuses to participate. It is the single biggest problem for sample surveys.	15
5176096936	Response Bias	Caused by a systematic pattern of incorrect responses in a sample survey	16
5176096937	Observational Study	A sample survey where individuals are observed and variables of interest are measured w/o an attempt to influence the response.	17
5176096938	Experiment	Deliberately imposes some treatment on individuals to measure their responses. They are the only source of fully convincing data when your goal is to understand cause and effect.	18
5176096939	Response Variable	Measures the outcome of a study	19
5176096940	Lurking Variable	A variable that is not among the explanatory or response variables in a study but may influence the response variable.	20
5176096941	Confounding	Occurs when 2 variables are associated in such a way that their effects on a response variable cannot be distinguished from each other.	21
5176096942	Treatment	A specific condition applied to the individuals in an experiment.	22
5176096943	Experimental Units	Smallest collection of individuals to which treatments are applied. If human, they are called subjects.	23
5176096944	Factors	The explanatory variables in an experiment	24
5176096945	Comparative Experiment	Compare 2 or more treatments	25
5176096946	Random Assignment	Experimental units are assigned to treatments at random, using some sort of chance process	26
5176096947	Completely Randomized Design	Treatments are assigned to all experimental units completely by chance	27
5176096948	Control Group	Provides a baseline for comparing the effects of the other treatments.	28
5176096949	What are the 3 principles of Experimental Design?	1) Control 2) Randomization 3) Replication	29
5176096950	Replication	Using enough experimental units to distinguish a difference in the effects of the treatments from chance variation.	30
5176096951	Placebo	Does not have an active ingredient...e.g. sugar pill	31
5176096952	Placebo Effect	A fake treatment that results in subjects reporting a response expected from the real treatment	32
5176096953	Double-Blind	Neither the subjects or those who interact with them and measure the response variable know which treament the subject received	33
5176096954	Single Blind	One side is blind - either the subject or the researcher. The researchers taking measurements do not know if the subject is in the control or treatment group OR the subject does not know	34
5176096955	Statistically Significant	An observed effect so large that it would rarely occur by chance	35
5176096956	Blocking	A form of control. Grouping similar experimental units together that are know before the experiment to be similar in some way and expected to affect the response to treatments	36
5176096957	Randomized Block Design	Reduces the effect of variation among experimental units. e.g. separate laundry into white and color then randomly assign 1/2 of each block to be washed in hot or cold water.	37
5176096958	Matched Pairs Design	A common type of randomized block design for comparing 2 treatments. In some matched pairs design, each subject receives both treatments in a random order. In others, subjects are matched up in pairs as closely as possible and each subject in the pair receives one of the treatments.	38