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26 Cards in this Set
- Front
- Back
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Define Mode.
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The most commonly occurring value.
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a) Define Median
b) How do you find middle value? |
a) The middle value when the data is in ascending/descending order
b) Add 1, divide by 2 |
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Define range.
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Difference between highest and lowest (highest minus lowest).
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How do you do a tally chart?
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>Do a column to show group labels, most probably class intervals, i.e. 50<60
>Do a second column to show the tally >Do a third column to show frequency (the number of tally's). |
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Define class boundaries.
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The precise values where you pass from one group into the next, i.e. 51<60, 61<70, class boundary = 60.5
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Define mid-interval value.
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The exact middle between intervals i.e. 51<60 = 55.5
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What two points should you remember when plotting a cumulative frequency graph?
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>Always plot points using the highest value from intervals of each group
>Cumulative Frequency is always plotted up the side |
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How do you find the median on a cumulative frequency graph?
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Exactly half way up the side then across, then down and read off value
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How do you find the lower and upper quartile on a cumulative frequency graph?
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Exactly 1/4 and 3/4 up the side, then across, then down and read off value
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How do you find the interquartile range on a cumulative frequency graph?
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The distance on the bottom scale between the lower and upper quartiles.
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If a histogram is symmetrical what would you use for average?
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Mean or median
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What can you find from the middle of a histogram?
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Mean
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What do you always do with a frequency polygon?
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Plot mid-points
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What does a box plot look like?
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How do you plot a histogram?
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Add a column called frequency density which is frequency divided by the range of the interval. Its not height but area when drawing graph
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What does a stem and leaf look like?
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What does a scatter graph look like?
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What does dispersion on a histogram mean?
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Define Mean.
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TOTAL of items / NUMBER of items
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How do you do a frequency table?
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Just multiply the two columns to make a third column titled, No x Frequency. If there's a tally column ignore it.
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How do you find the mean using a frequency table?
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Mean = 3rd Row Total / 2nd Row Total
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How do you find the median using a frequency table?
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Total of the frequency + 1 / 2, then starting with the first row frequency keep adding each frequency row until you get the number from the previous calculation, first column = median
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How do you find the mode using a frequency table?
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Mode = row with the highest frequency
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How do you find the range using a frequency table?
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Difference between top row and bottom row of 1st column
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How do you estimate the mean from grouped frequency tables?
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>Add a 3rd row consisting of mid-interval values
>Add a 4th row consisting of Frequency x Mid-Interval Value >Mean = Total of Freq x Mid-interval column / Total of Freq column |
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How do you do cumulative frequency?
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Add another column with a running total of the frequency.
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