Terms Definitions
Geometric mean
Having two modes
Having one mode
Measure of a population
Experimentation where groups of subjects are divided into "blocks" and tested upon within each of these blocks
Having more than two modes
Random variable
Represents the different numbers associated with potential outcomes of certain scenarios
Random variables that can assume values throughout the whole line interval
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)
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
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
When both the subjects nor those evaluating their responses know which treatment the subject has received
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
Values that lie up 1/10th and 9/10th of the way up a list; have percentile ranks of 10% and 90%
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
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
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
A pretend experiment
systematically favors certain outcomes
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
(statistics) the entire aggregation of items from which samples can be drawn
that chance of an event occurring
some portion of the intended population is either unrepresented or under-represented
Response Variable
Measures an outcome of a study
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
something presented as a drug (or whatever you are trying to test in your experiment), but having no actual effect on the person.
The part of the population actually examined in order to gather information.
mean of a density curve
The balance point.
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!!
degree to which two variables are associated
Studying a part in order to gain information about the whole
When the levels of one factor are associated with the levels of another factor in such a way that their effects cannot be seperated.
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
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.
B1 gives a vlue in y units per x
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
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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