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38 Cards in this Set
- Front
- Back
Define: casual variable
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Independent variable that produces a casual effect on the dependent variable (we cannot prove in this class)
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Define: confounding variable
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Extraneous variable that correlates with both the independent and dependent variable (cannot prove in this class)
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Define: bell curve
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Symmetric distribution
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If you are preforming a study and you want to see if it is rare to get 12 bets in a sample of 20 what two formulas would you use?
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-First, count(Risk_Taker="Yes")
-Second, (number_of_bets_in_a_random_20<12)/(number_of_bets_in_a_random_20) |
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How do you write a conclusion?
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The probability of a random collection of __ having __ or less/more is (p-value). This is evidence that the experimentally observed correlation between __ and __ is (or is not) caused by random variation alone.
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What is a summary table and how do you caption it?
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-Describes experiment
-Date/time, location, circumstance, ect. |
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What is a table and how do you caption it?
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-Things you're measuring
-Measure count, mean, median |
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What is a graph and how do you caption it?
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-Shows pattern of data
-Label axes, describe interesting features |
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Where is the independent and dependent variable on a summary table and graph?
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-Independent on horizontal and bottom of graph
-Dependent on vertical |
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What are the two categories of descriptive statistics?
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1.Meausre of central tendencies=trying to summarize data by "typical" value
2.Measure of dispersion=indicate through a single number the extent to which a distributions observations vary |
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What are the measures used in central tendencies?
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Mean, median
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What are the measures used in dispersion?
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Standard deviation, IQR
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Define: mean
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The mean of a random sample is defined as the sum of the observed values divided by the sum of the sample
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Define: median
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Arrange data points in ascending order, the median is the middle observation
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What's the equation for standard deviation?
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Square root of (x-xbar)squared/n-1 where n=sample size, x=observed value, and xbar=sample mean
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What are Q1, Q2, and Q3?
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-Q1=data point below which 25% of data is
-Q2=data point below which 50% of data is -Q3=data point below which 75% of data is |
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What is the equation for IQR?
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Q3-Q1
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Define: outlier
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Extreme values not considered common values
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Define: whiskers
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Lines extending from the box plot
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Define: right-skewed distribution
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Positive skewed distribution with longer right tail
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Define: left-skewed distribution
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Negative skewed distribution witha longer left tail
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Define: symmetric
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Distribution will have approx. equal tails
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What are the equations to calculate outliers?
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-Q1-1.5(IQR) (left outliers)
-Q3+1.5IQR (right outliers) |
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Define: explanatory variable
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Variable that is manipulated by the experiment, supposed to "explain" the other variable
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Define: response variable
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Variable that occurs as a result of the explanatory variable
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Define: frequency table
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A table that displays the frequency of different observations, organizes data
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Define: dichotomos data
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Data in which observations can only be one of two things
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Define: categorical data
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Data in which observations fit in finite categories
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Define: quantitative data
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Data in which observations take a numerical value
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Define: odds ratio
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-Ratio of the odds of one group and another group
-p(1-p)/q(1-q) |
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Define: p-value (relative frequency)
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The probability that the results from an experiment are entirely due to chance
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Define: measure of a sample
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A single number that summarizes a sample
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Define: randomized distribution
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A distribution applied to many random samples of data
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How do you assess two dichotomous variables?
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-2x2 frequency table
-Bar graph -We can sample |
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How do you assess one continuous variable?
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-5 number summary
-Box plot -Can't sample |
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How do you assess two continuous variables
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-5 number summary
-Histogram or box plot -No |
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Can we assess 3 variables?
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No not yet
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How do you assess one dichotomous and one continuous variable?
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-5 number summary, count and mean
-Histogram or box plot -We can sample |