Stat2

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What is voluntary response sample?
A sample in which the subjects themselves decide whether to be included in the study.
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Which of the following is typically the important factor to consider when conducting a statistical analysis of data?
1. Sampling method 2. Context of the data 3. Source of the data
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What does it mean for the findings of a statistical analysis of data to be statistically significant?
The likelihood of getting these results by chance is very small.
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Sampling method
If we are collecting sample data for a study, the _ that we choose can greatly influence the validity of our conclusions. For example, we can use sound statistical methods to analyze data in voluntary response samples, but the results are not necessarily valid.
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How do parameter and statistic differ?
A parameter is a numerical measurement of a population; a statistic is a numerical measurement of a sample.
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Which of the following is associated with a parameter?
Data that were obtained from an entire population.
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Why is a voluntary response sample generally unsuitable for methods of statistics?
People with special interests are more likely to respond, so the sample is likely to be biased.
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What is the goal of learning statistics?
To learn to distinguish between statistical conclusions that are likely to be valid and those that are seriously flawed.
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What is a self-interest study?
A survey in which the sponsor can enjoy monetary or other gains from the results.
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What is the difference between a random sample and a simple random sample?
With a random sample, each individual has the same chance of being selected. With a simple random sample, all samples of the same size have the same chance of being selected.
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Which sampling method divides the population up into sections, randomly selects some of those sections, then choose all the members from the selected sections to study?
Cluster
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Which sampling method subdivides the population into categories sharing similar characteristics and then selects a sample from each subdivision?
Stratified
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Randomization
_is used when subjects are assigned to different groups through a process of random selection.
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Which of the following corresponds to the case when every sample of size n has the same chance of being chosen?
Simple random sample
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Which characteristic of data is a measure of the amount that the data values vary?
Variation
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Outliers
_are sample values that lie very far away from the majority of the other sample values.
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Frequency distribution
A frequency distribution helps us understand the nature of the distribution of a data set.
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Class width is found by
subtracting a lower class limit from the next consecutive lower class limit
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relative frequency
In a relative frequency distribution, the frequency of a class is replaced with a proportion or percent.
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frequency
The heights of the bars of a histogram correspond to frequency values.
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touch
The bars in a histogram touch.
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shape of the distribution
A histogram aids in analyzing the _ of the data.
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relative frequency
A _ histogram has the same shape and horizontal scale as a histogram but the vertical scale is marked with relative frequencies instead of actual frequency.
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normal
A(n)_distribution has a "bell" shape.
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What are some advantages of a dotplot over a frequency polygon
A dotplot allows you to identify the original data values.
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frequency polygon
A(n)_uses line segments to connect points located directly above class midpoint values.
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dotplot
A_is a graph of each data value plotted as a point.
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graphs
We utilize statistical _ to look for features that reveal some useful or interesting characteristics of the data set.
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scatterplot
A _ is a plot of paired data (x,y) and is helpful in determining whether there is a relationship between the two variables.
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a nonzero axis
In a graph, if one or both axes begin at some value other than zero, the differences are exaggerated. This bad graphing method is known as _
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pictographs
When drawings of objects are used to depict data, false impressions can be made. These drawings are called _
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Which of the following is a common distortion that occurs in graphs
Using a two-dimensional object to represent data that are one-dimensional in nature.
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So that we can critically analyze a graph to determine whether it is misleading.
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descriptive
Methods used that summarize or describe characteristics of data are called _ statistics.
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measure of center
A value at the center or middle of a data set is a(n) _
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mode
The measure of center that is the value that occurs with the greatest frequency is the _
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Range
The measure of variation that is very sensitive to extreme values
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s=range/4
The Range Rule of Thumb roughly estimates the standard deviation of a data set as _
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the Empirical Rule
For data sets having a distribution that is approximately bell-shaped, _ states that about 68% of all data values fall within one standard deviation from the mean.
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variance
The square of the standard deviation is called the_
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z-score
When a data value is converted to a standardized scale representing the number of standard deviations the data value lies from the mean, we call the new value a _
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unusual
A data value is considered _ if its z-score is less than -2 or greater than 2
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the corresponding z-score is negative
Whenever a data value is less than the mean, _
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outlier
In modified boxplots, a data value is a(n) outlier if it is above Q3+(1.5)(IQR) or below Q1-(1.5)(IQR).
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sample space
The _ for a procedure consists of all possible simple events or all outcomes that cannot be broken down any further.
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equally likely
The classical approach to probability requires that the outcomes are _
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the law of large numbers
As a procedure is repeated again and again, the relative frequency of an event tends to approach the actual probability. This is known as _
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actual odds in favor of
The _ event A occurring are the ratio P(A)/(P(A-)
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When using the _ always be careful to avoid double-counting outcomes.
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disjoint
Events that are _ cannot occur at the same time
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rule of complementary events
P(A) + P(A-) = 1 is one way to express the _
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P(A or B) indicates
the probability that in a single trial, event A occurs, event B occurs, or they both occur.
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compound event
A _ is any event combining two or more simple events.
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Describe what the notation P(BlA) represents.
The probability of event B occurring, given that event A has already occurred.
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tree diagram
A picture of line segments branching out from one starting point illustrating the possible outcomes of a procedure is called a _
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independent
Two events A and B are _ if the occurrence of one does not affect the probability of the occurrence of the other.
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independent
Selections made with replacement are considered to be _
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"one ore more"
"At least one" is equivalent to_
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"none"