Terms  Definitions 

zscore 
(xmean)/standard deviation

Unimodal 
Having one mode (bump)

outlier 
an unusually different data point

Treatment 
the specific experimental condition applied to the units.

The strength of the linear relationship increases as r moves away from this number 
0

experiment 
a procedure for investigating the effect of experimental conditions (which are manipulated by the experimenter) on a response variable

Blocking 
using extraneous factors to create experimental groups that are similar with respect to those factors, thereby filtering out their effect

categorical (quantitative) graphs 
bar charts, pie charts

level 
the experimental values that are chosen for each factor

regression 
process of finding a regression equation

Explanatory Variable 
attempts to explain the observed outcomes

Multistage Sample 
When we combing several sampling methods

response bias 
preconceived notions of a person answering [a survey] which may alter the experiments purpose, anything in the survey design that influences the responses from the sample.

undercoverage 
occurs when some groups in the population are left out of the process of choosing the sample

Independent variable 
a variable in correlation and regression analysis that can be controlled or manipulated

histogram 
a display for quantitative data that uses adjacent bars to represent counts or percentages of values falling in each interval

Sampling 
observing or gathering data about a portion of the population. Can be very accurate if sampling is done correctly. Samples should be selected using a method of random selection.

Statistically Significant 
An observed effect so large that rarely occur by chance

frequency distribution 
a table that displays frequencies and sometimes relative and cumulative relative frequencies (categorical data), possible values (discrete numerical data), or class intervals (continuous data)

Area Principle 
Each data value should be represented by same amount of area

replicate 
each treatment on many units to reduce chance variation in the results

Third Quartile 
The median of the observations whose position in the ordered list is to the right of the location of the overall median.

Cluster sample 
a sample obtained by selecting a preexisting or natural group, called a cluster, and using the members in the cluster for the sample

frequency table 
lists the categories for a categorical variable and displays the counts for each category

Standard Normal Curve 
the standardized normal curve with parameters N(0,1)
mean = 0, standard deviation = 1 *Areas under the curve are listed along with standardized values on the Ztable (left tail areas) *Zvalue: a standardized measure in terms of standard deviations FORMULA: 
discrete variable 
variable that may assume only a countable, and usually finite, number of values

nonlinear data 
growth that cannot be described with a line. two types are: exponential and power

Observational Study 
A study based on data where no manipulation has been employed

Blind Experiment 
an experiment in which the subjects do not know whether they are members of the experimental group or the control group.

Random sample 
a sample obtained by using random or chance methods; a sample for which every member of the population has an equal chance of being selected

right skewed distribution 
a distribution with a concentration of data on the lower end and the tail on the right

Categorical Data 
data that is not numerical in nature, can be classified in groups.; disploayed in bar charts, pie charts, tables, etc.

population mean, mu 
the average x value in an entire population

Law of Large Numbers 
The long run probability will approach its theoretical probability

sample variance and standard deviation 
the most frequently used measures of variability for sample data

random variable 
a quantity that takes any of a set of values with specified probabilities.

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