##### Chapter 1-6 Vocab
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#### Complete list of Terms and Definitions for Chapter 1-6 Vocab

Terms Definitions
modified boxplot a display for quantitative data that graphs the five-number summary on an axis and shows outliers of they exist
double-blind when neither the subjects nor people who have contact with them know which treatment a subject received
intersection the event that all of the events occur
monotonic increasing function Preserves the order of data. That is, if a > b, then f(a) > f(b)
probability the proportion of times the outcome would occur in a very long series of repetitions
pth percentile the value such that p percent of the observations fall underneath or at it (median is 50th percentile)
probability model a mathematical description of a random phenomenon consisting of a sample space and a way of assigning probabilities to events
placebo a dummy treatment
five-number-summary A summary of a data set that includes the minimum, lower quartile, median, upper quartile, and maximum.
union the event that at least one of the collection occurs
conditional probability the probability that an event will occur given that one or more other events have occurred
left-skewed A density curve where the left side of the distribution extends in a long tail. (Mean < median.)
monotonic function moves in one direction as its argument t increases, Moves in one direction as its argument t increases
subjects what the units are called when they are human beings
study an experiment when we actually do something to people, animals, objects in order to observe the response
factor the explanatory variables in an experiment
block a group of experimental units or subjects that are known before the experiment to be similar in some way that is expected to affect the response to the treatments
variable any characteristics of an individual
quantitative variable takes numerical values for which arithmetic operations such as adding and averaging make sense
distribution tells you what values the variable takes and how often it takes these values
third quartile the median of the upper half of the data
randomize use impersonal chance to assign experimental units to treatments
right-skewed Right tail of a graph is longer than the left; mean > median
explanatory data analysis using statistical tools and ideas to help you examine data in order to describe their main features
slope the rate of change.
probability sample a sample chosen by chance
lurking variable a variable that is not among the explanatory or response variables in a study and yet may influence the interpretation of relationships among those variables
curved pattern shows that the relationship is not linear
population the entire group of individuals that we want information about
histogram a bar chart representing a frequency distribution.
outlier an individual observation that falls outside the overall pattern of the graph
extrapolation the use of regression line for prediction far outside the domain of values of the explanatory variable(x) that you used to obtain the line or curve.
voluntary response sample consists of people who choose themselves by responding to a general appeal
correlation measures the direction and strength of the linear relationship between two quantitative variables.
monotonic decreasing function Reverses the order of data. That is, if a > b, then f(a) < f(b)
symmetric having similarity in size, shape, and relative position of corresponding parts.
z score a measure of how many standard deviations you are away from the norm (average or mean)
normal probability plot a display to help assess whether a distribution of data is approximately normal; if it is nearly straight, the data satisfy the nearly normal condition
nonresponse occurs when an individual chosen for the sample can't be contacted or does not cooperate
explanatory variable a variable that is being manipulated by the researcher in order to see if it affects the outcome variable
sampling involves studying a part in order to gain information about the whole
exponential growth increases by a fixed percentage of the previous total
dotplot a type of graph used to display quantitative data, graphs a dot for each case against a single axis
undercoverage occurs when some groups in the population are left out of the process of choosing the sample
statistical inference answers specific questions with a known degree of confidence
statistics the science of data
Interquartile range Q3-Q1
statistical significance an observed effect so large that it would rarely occur by chance
random when individual outcomes are uncertain
outlier an observation that lies outside the overall pattern of the other observations
influential observations individual points that substantially change the regression line
bias when the design of a study is systematically favors certain outcomes' systematic favoritism towards one outcome.
time plot plots each observation against the time at which it was measured
trend a long-term upward or downward movement over time
simulation the imitation of chance behavior, based on a model that accurately reflects the experiment under consideration
convenience sampling chooses the individuals easiest to reach
independent knowing that one event occuring does not change the probability that we would assign to the other event
median the midpoint of a distribution
probability model Used to calculate theoretical answer.
density curve a curve with an area of exactly 1 (100%) beneath it; alawys on or above the horizontal axis; median divides area under curve in half; mean is the 'balance point'; when mean and median are the same, curve is symmetric
percentile A point on the distributionbelow with a certain % of scores fall. Ex: Scored in the 99th percentile = only 1% scored higher than you
ogive a line graph of a cumulative frequency or cumulative relative frequency distribution.
observational study observes individuals and measures variables of interest but does not attempt to influence the responses
least-squares regression line the line that makes the sum of the squares of the vertical distances of the data points from the line as small as possible
categorical variable places an individual into one of several groups or categories
standard deviation the square root of the variance
response variable measures an outcome of a study
strata groups of similar individuals
sample space the set of all possible outcomes
block design the random assignment of units to treatments is carried out separately within each block
complement the event does not occur
residual the scatterplot of the regression residuals against the explanatory variable
lack of realism the most serious potential weakness of experiments
event any outcome or a set of outcomes of a random phenomenon
randomization the use of chance to divide experimental units into groups
experimental units the individuals on which the experiment is done
first quartile the median of the lower half of the data
Simpson's paradox refers to the reversal of the direction of a comparison or an association when data from several groups are combined to form a single group
sample items selected at random from a population and used to test hypotheses about the population
census attempts to contact every individual in the entire population
disjoint events events that have no outcomes in common
simple random sample consists of individuals from the population chosen in such a way that every set of individuals has a equal chance to be the sample actually selected
individuals the objects described by a set of data
confounding variables factors that cause differences between the experimental group and the control group other than the independent variable
matched pairs a common form of blocking for comparing just two treatments
seasonal variation a pattern that repeats itself at regular time intervals
joint probability the probability of two events occurring together
mean the ordinary arithmetic average or most common measure of center
intercept the value of y hat when x= 0
tree diagram a branching diagram that shows all possible combinations or outcomes of an event
sample design refers to the method used to choose the sample from the population
scatterplot a graphed cluster of dots, each of which represents the values of two quantitative variables.
transforming/reexpressing applying a function such as the logarithm or square root to a quantitative transforming variable
linear growth increases by a fixed amount in each equal time period
experiment A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process
joint event simultaneous occurence of two events; probability is called a joint probability
treatment a specific experimental condition applied to the units