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| A characteristic or measure obtained by using the data values from a sample. |
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| A characteristic or measure obtained by using all the data values from a specific population. |
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| A rule of statistics which states that when computations are done in a calculation, rounding should not be done until the final answer is calculated. |
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| Mean (arithmetic average) |
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Definition
Sample Mean
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Population Mean
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Definition
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| Finding Grouped Mean Calcutation |
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| The midpoint of a data array. |
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| The value that occurs most often in a data set. |
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| The class which has the largest frequency. Sometimes the midpoint of the class is used rather than the boundaries. |
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Definition
The sum of the lowest and the highest values in the data set, divided by 2.
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Definition
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| Positively / Right Skewed Distribution |
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Definition
A distribution in which the majority of the data values fall to the left of the mean and cluster at the lower end of the distribution. The mean is to the right of the median, and the mode is to the left of the median.
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Term
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Definition
Distribution in which the data values are evenly distributed on both sides of the mean. Can be called unimodal if the mean, median, and mode are the same and are at the center of the distribution.
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| Negatively / Left Skewed Distribution |
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Definition
A distribution in which a majority of the data falls to the right of the mean and clusters at the upper end of the distribution, with the tail to the left. The mean is to the left of the median, and the mode is to the right of the median.
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Term
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Definition
The highest value minus the lowest value
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| Rounding Rule for Standard Deviation |
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Definition
| The final answer should be rounded to one more decimal place than that of the original data. |
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Term
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Definition
sample mean
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population mean
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1. Find the mean
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2. Subtract the mean from each data value
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3. Square Each Result
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4. Find the sum of the squares
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5. Divide the sum by N to get the variance
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Term
| Population Variance Formula |
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Definition
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Term
| Population Standard Deviation |
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Definition
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Definition
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| Sample Standard Deviation |
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Definition
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| Sample Computational Formula for Standard Deviation |
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Definition
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Grouped Data
Variance and Standard Deviation |
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Definition
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Definition
| Average of the squares of the distance that each value is from the mean. |
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Definition
The square root of the variance.
or
The square root of the average of the squares of the distance that each value is from the mean. |
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Definition
A statistic that allows you to compare standard deviation when the units are different.
Standard deviation / mean
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Term
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Definition
The proportion of values from a data set that will fall within k standard devations from the mean will be at least 1 - 1/k2, where k is a number greater than 1 (k is not necessarily an integer).
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Term
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Definition
| Rule which states that when a distribution is bell-shaped (normal) the following rules are true: 68% of data values fall within 1 standard deviation, 95% within 2 standard deviations, and 99.7% within 3 standard deviations. |
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Definition
A measure of relative position obtained by subtracting the mean from the value and dividing the result by the standard deviation.
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Definition
Data divided into a set of 100 equal groups
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2,3,5,6,8,10,12,15,18,20
since there are six numbers below a score of 12 then
Percentile = 6+0.5/10*100 = 65th percentile
Compute percentile
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Term
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Definition
| Data divided into four groups, separated by Q1, Q2, Q3. Q2=MD |
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Term
| Interquartile Range (IQR) |
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Definition
| The difference between Q1 and Q3 and is the range of the middle 50% of the data. |
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Definition
| The distribution of data in to 10 groups. They are denoted as D1, D2, etc. |
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Definition
1. lowest value of the data set - minimum
2. Q1
3. Median - Q2
4. Q3
5. highest value of the data set - maximum |
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Term
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Definition
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Outliers = Q1 - 1.5(IQR) or Q3 + 1.5(IQR)
Extreme Outliers = Q1 - 3(IQR) or Q3 + 3(IQR) |
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