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43 Cards in this Set
- Front
- Back
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Association
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Values of one variable tend to occur with certain values of another. Conditional distributions differ from marginal
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Bivariate data
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data collected on two variables for each individual in a study
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CLT
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When sampling from a non-Normal population, the sampling distribution of is approximately Normal whenever the sample is large and random.
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conditional distribution:
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The distribution of the values in a single row (or a single column) of a two-way table.
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correlation coefficient
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A measure of the strength of the linear relationship between two quantitative variables.
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law of large numbers:
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The fact that the average ( ) of observed values in a sample will get closer and closer
to μ as the sample size increases. |
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least squares:
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A method for finding the equation of a line that minimizes the sum of squared residuals.
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least squares regression line:
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The line with the smallest sum of squared residuals.
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marginal distribution:
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The distribution of the values in the “total” row (or the “total” column) of a two-way
table. |
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parameter
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A characteristic of a population that is usually unknown; this could be mean, median, proportion,
standard deviation computed on all the data from the population.; a parameter does not have variability. |
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parameter symbols:
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μ, σ, and p (mean of population, standard deviation of population, proportion of a
population, respectively) |
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probability of an outcome:
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A measure of the proportion of times an outcome occurs in a very long series of
repetitions that gives us an indication of the likelihood of the outcome. |
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process:
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Sequence of operations used in production, manufacturing, etc.
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process in statistical control:
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A process whose inputs and outputs exhibit natural variation when observed over
time. |
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quality control chart:
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A chart plotting the means of regular samples of size n against time; this chart is used
to access whether the process is in control. |
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quantitative bivariate needs what type of analysis?
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The type of data required for regression analysis.
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r
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The symbol for correlation coefficient.
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r2:
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The percentage of total variation in the response variable, Y, that is explained by the regression equation; in
other words, the percentage of total variation in the response variable, Y, that is explained by the explanatory variable, X. |
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random:
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A phenomenon that describes the uncertainty of individual outcomes in the short run, but gives a regular distribution of the outcomes in the long run.
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random variable:
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A variable whose value is a numerical outcome of a random phenomenon.
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regression equation
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A formula for a line that models a linear relationship between two quantitative variables.
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residual
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The observed y minus the predicted y; denoted: y ; prediction error
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sample mean, x bar :
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The random variable of the sampling distribution of xbar .
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sampling distribution
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A distribution of a statistic; a list of all the possible values of a statistic together with
the frequency (or probability) of each value. |
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sampling distribution of xbar
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A list of all the possible values for xbar together with the frequency (or probability) of each value; in other words, the distribution of all xbar’s from all possible samples.
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sampling variability:
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The variability of sample results from one sample to the next; something we must
measure in order to effectively do inference. |
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scatterplot:
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A two dimensional plot used to examine strength of relationship between two variables as well as
direction and type of relationship. |
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simulation:
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Using random numbers to imitate chance behavior.
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slope:
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A measure of the average change in the response variable for every one unit increase in the explanatory
or independent variable. |
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standard deviation of xbar (also called the standard deviation of the sampling distribution of xbar)
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A measure of the variability of the values of the statistic xbar about μ; a measure of the variability of the sampling distribution of xbar; in other words, the Aaverage@ amount that the statistic, xbar , deviates from its
mean μ. Computed as sigma/square root n. |
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statistic
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A number computed from sample data (without any knowledge of the value of a parameter) used to estimate the value of the parameter.
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statistic symbols
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xbar , s, p-hat (mean of sample, standard deviation of sample, proportion of sample, respectively)
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statistical process control:
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A procedure used to check a process at regular intervals to detect problems and correct them before they become serious.
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sum of squared residuals (or error):
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the residuals are squared and added.
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total variation in Y
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The sum of the squared deviations of the Y observations about their mean, y-hat.
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two-way table
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A table containing counts for two categorical variables. It has r rows and c columns.
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unexplained variation
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The sum of squared residuals
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fun facts about r
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gives direction and strength of linear relationship between x & y
affected by outliers association NOT causation Need quantitative range from -1 to 1 0=not linear x predict y, y predict x needs to be quantitative variables no units |
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Theoretical Sampling distribution of xbar
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All x bar values from ALL possible sample of the same size from the population, and miu=xbar
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As n increases, what happens to sd?
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it decreases.
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What does this notation mean? N(1.0875, 0.015)
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N=Normal
1.0875 is mean .015 is SDm |
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mean of sampling distribution ALWAYS equals miu
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always!
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Remember CLT does not compute probablilities on DATA Rather sample MEANS
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yup
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