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22 Cards in this Set
- Front
- Back
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What is descriptive statistics used for? |
To characterize or describe data |
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What is inferential statistics used for? |
To make decisions to generalize beyond the data |
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What is a frequency table? |
Used to summarize data, it is used to show how often each value occurs |
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What does a histogram display? |
It is a visual display of a frequency table |
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In terms of histograms and frequency polygons, name three different shapes of distributions. |
1. Unimodal 3. Rectangular |
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What is a ceiling effect? And in what direction is it likely to be skewed in? |
A limitation in the high end of the scale. |
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What is a floor effect? |
Limitation in the low end of the scale -Negative (left) skew |
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What is a Z-score? |
The number of standard deviations a score is, above or below the mean. |
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Z scores provide a standard measurement scale for psychological variables. Any set of scores is transformed into a distribution with a mean of what and std. dev. of what? |
A distribution with a mean of 0 and std. dev. of 1 |
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What does a scatter diagram (scatter plot) represent? |
The relationship between two variables |
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What is the correlation coefficient a measure of? |
Describes the degree and direction of a linear correlation |
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In relation to z-scores, what is the correlation coefficient? |
The average of the cross-products of z-scores. |
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What is the measure used to compare correlations? |
The proportionate reduction in error |
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What are two factors which can artifactually reduce the size of a correlation? |
1. Restriction in range: when narrow set of values on a variable included |
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How does bi variate and multiple regression differ? |
One is used when scores on one variable are used to predict scores on another variable, whereas the other is used when two or more variables are used to predict scores on another variable. |
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What is the goal of regression? |
To find the linear line which best describes the relationship between x an y. |
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What does the 'a' represent in the regression model formula? |
The regression constant (intercept) |
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What does the 'b' represent in the regression model formula? |
The regression coefficient (slope) |
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What is the standard regression model used for? |
Uses Z scores to make predictions rather than raw scores. |
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What is 'error' in predictions? |
The difference between the actual and predicted value for Y |
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What is the total amount of error in a prediction? |
The sum of the squared errors |
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In bivariate regression, what is the proportionate reduction in error a measure of? |
How accurate our linear prediction model is predicting the data |
