[20/09/12] Stem and Leaf * Key is essential! * Display discrete data * Continuous is ok but round it off to either nearest whole number or 1/2 d.p) * Can be plotted into a box plot * Can find * Median (Q₂) * Range * Quartiles (Q₁‚ Q₂‚ Q₃) * Inter-quartile Range * Excludes outliers * Middle 50% of data * Percentiles * Outliers (Extreme values) * Ordered data Cumulative Frequency Diagrams
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of values. For the checking balances the mean is 1499.87 while the median is 1604.50. The highest mean and median is in Atlanta‚ followed by Erie‚ then Louisville and finally Cincinnati. Atlanta has a high mean and median compared to the other cities who have means and medians that are relatively close in value. All four cities‚ have different numbers of accounts so it is hard to compare them. The median of a data is the middle number when the set is sorted in numerical order and
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This measure is the measures of position or central tendency‚ it is use to see how a large set of raw materials can be summarized so that the meaningful essential can be extracted from it. The most commonly measures of central tendency are the mean‚ median‚ and mode. Properties of the Arithmetic Mean easy to compute easy to understand valuable in statistical tool strongly influence by extreme values‚ this is particularly true when the number of cases is small cannot be compute when distribution
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(Note that the right endpoint should be fixed so that the total area under the curve is 1. This is required for a valid density curve.) b. Determine the median‚ the first quartile (Q1)‚ and the third quartile (Q3). c. Relative to the median‚ where would you expect the mean of the distribution to lie? Explain briefly. The distribution is skewed left‚ so the mean will be left of the median. d. What percent of the observations lie below 0.5? Above 1.5? 2. The following are the salaries of employees in a small business:
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minimal? ‘Minimal’ because if we had used any other value than the mean (5) to subtract‚ SS would have been larger than 42 MEDIAN A second measure of central tendency: the median (ordinal) to find the median: 1) sort all cases based on their value on x 2) the value of the „middle case“ equals the median (equal amount of cases below and above) Note that the median is not responsive to outliers
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smallest to largest. Once I had done this I split both sets of my data up into the upper quartile‚ lower quartile and I found the median which was my 20th bit of data. After I had done this I then worked out my interquartile range by taking my lower quartile away from my upper quartile which gave me the interquartile range. I got the upper and lower quartile and median by ordering my data and then splitting it up into quarters. I then recorded my highest and lowest values because this gives me the
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tendency. In cases of great skewness‚ use the median as the measure of central tendency to avoid distortion by extreme values. You can usually assess skewness by simply eyeballing a histogram. To be precise about measuring skewness‚ apply the Excel SKEW function to a data set. * If SKEW > +1‚ the data are positively skewed and the median is the better measure of central tendency. * If SKEW < -1‚ the data are negatively skewed and the median is again the better measure of central tendency
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divide by number of data values Median = list data vlues in order‚ locate middle data value 2. Range = Maximum – minimum Interquartile range (IQR) = Q3 –Q1 Standard deviation is the average distance values fall from the mean of graph. 3. Q1(lower quartile) is the 25th percentile of ordered data or median of lower half of ordered data Median (Q2) is the 50th percentile of ordered data Q3 (upper quartile) is the 75th percentile of ordered data or median of upper half of ordered data Z
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Bottle Company Case Study Daniel James Jr. Math 300 – Statistics Professor Issam MerhiStrayer University August 17‚ 2014 Mean‚ Median and Standard Deviation Explaining the make up a data description one must calculate the mean‚ median and standard deviation. To determine the mean‚ also known as the arithmetic average‚ is found by adding the value of the data and diving by the total numbers of values. In this case of a Bottle company study with thirty different bottles. The mean is 15.2‚
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to the right (Positively skewed) Mode < Median < Mean b) Skewed to the left (Negatively skewed) Mode > Median > Mean c) Symmetric Distribution Mode = Median = Mean Measures of Central Tendency: The Mean‚ Mode and Median The mean is the average of scores: Population mean: μ = Σ xi/N Sample mean: x = Σ xi/n The mode is the value that has the highest frequency The median is the middle value of data ordered from lowest to highest The median and the mode are relatively less sensitive
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