Question | Answer |
What is a quantitative variable? | A variable that is associated with numerical observations. |
What is a qualitative variable? | A variable that is associated with non-numerical observations. |
What is a discrete variable? | A variable that can take only specific values in a given range. |
What is a continuous variable? | A variable that can take any value in a given range. |
What is a measure of location? | A way a set of data can be summarised by giving a single number to describe its centre. |
What are the 3 measures of location? | Mode, median and mean. |
How do you work out the median of DISCRETE data? | 1. Divide the total no. of observations by 2. 2. If n/2 is a WHOLE number, find the midpoint of the term and the term above. 3. If n/2 is NOT A WHOLE NUMBER, round the number up and pick the corresponding term. |
E.G. of the previous flashcard. | |
How do you work out the mean of DISCRETE data? | |
What is the formula for working out the combined mean? | |
When should you use the mode? | -Used when the data is qualitative. -Not very informative if each value occurs only once. |
When should you use the median? | -Used for quantitative data. -Usually used when there are extreme values as they do not affect it. |
When should you use the mean? | -Used for quantitative data and uses all the pieces of data. -Gives a true measure of the data. -Affected by extreme values. |
How do you find the mean of grouped continuous data? | Where x is the mid-point of the class. |
How do you find the median of grouped continuous data? | -Divide n by 2. -Use interpolation to find the value of the corresponding term. |
What does the line method look like for interpolation? | |
What is the formula for interpolation? | |
What MUST you be careful of when interpolating? | Using the CORRECT class boundaries. If there is a gap, find the mid-point between the classes. If not, use the values of the classes. |
What is the modal class? | The class with the highest frequency. |
In coding, how do you find the mean of the original data? | 1. Find mean of coded data. 2. Equate this to the coding used. 3. Solve. |
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