SESN+8+ASSIGN-1

Fall 2014-SESSION 8 LECTURE and ASSIGNMENTS-１

上の方. ..

Histogram http://www.shodor.org/interactivate/activities/Histogram/

p228 .


 * CD || how many people? ||  ||
 * 0 || 7 ||  ||
 * 1 ||  ||   ||
 * 2 || 1 ||  ||
 * 3 || 1 ||  ||
 * 4 || 3 ||  ||
 * 5 || 1 ||  ||
 * 6 || 1 ||  ||
 * 7 ||  ||   ||
 * 8 || 2 ||  ||
 * 9 || 1 ||  ||
 * 10 ||  ||   ||
 * 11 || 1 ||  ||
 * 12 || 1 ||  ||
 * 84 || 1 ||  ||
 * || 20 total # ||  ||
 * || 20 total # ||  ||

Compact disk ownership


 * Min Frequency = 0
 * Max Frequency = 7
 * N = 20
 * Mean = 8.000
 * SD = 17.849
 * Minimum valuable of X-axis = -4.667



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=ーー　答え　ーー=
 * Range = 0~84 (take highest/lowest # = range 2~12)
 * Variability of responses = 12-2+1 = 11
 * ってことかな？？？

=ーー　答え　終了ーー= .

Compact disk ownership 0 4 3 9 6 0 0 84 2 11 0 0 8 5 0 0 4 12 4 8

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p229

. Compact disk ownership


 * Min Frequency = 0
 * Max Frequency = 7
 * N = 20
 * Mean = 8.000
 * SD = 17.849
 * Minimum valuable of X-axis = -4.667

=ーー　答え　ーー= What is the mean # of CDs for this sample? --> Mean = 8.000 (= average)

=ーー　答え　終了ーー= .

--- =ーー　答え　ーー=

What is the mode # of CDs for this sample? --> mode = 0 CD = 7people (もし前後カットして考えるなら、4CD = 3 people） What is the median # of CDs for this sample? --> median= ４CD

Which average do you think is best to describe the results of this survey? why?

Would it be the best for all surveys? why? why not?

=ーー　答え　終了ーー= .

http://graphpad.com/quickcalcs/oneSampleT1/?Format=C

One sample //t// test results
The two-tailed P value equals 0.0656 By conventional criteria, this difference is considered to be not quite statistically significant.
 * **P value and statistical significance:**

The actual mean is 8.00 The difference between these two values is 8.00 The 95% confidence interval of this difference: From -0.57 to 16.57
 * Confidence interval:**
 * //__The hypothetical mean is 0.00__//**

t = 1.9536 df = 19 standard error of difference = 4.095
 * Intermediate values used in calculations:**

GraphPad's web site includes portions of the manual for GraphPad Prism that can help you learn statistics. First, review the meaning of [|P values] and [|confidence intervals]. Then learn how to interpret results from a [|one sample //t// test].
 * Learn more:**


 * Review your data:** ||

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 * Mean || 8.00 ||
 * SD || 18.31 ||
 * SEM || 4.09 ||
 * N || 20 ||

One sample //t// test results
The two-tailed P value equals 0.1037 By conventional criteria, this difference is considered to be not statistically significant.
 * **P value and statistical significance:**

__//**The hypothetical mean is 1.00**//__ The actual mean is 8.00 The difference between these two values is 7.00 The 95% confidence interval of this difference: From -1.57 to 15.57
 * Confidence interval:**

t = 1.7094 df = 19 standard error of difference = 4.095
 * Intermediate values used in calculations:**

GraphPad's web site includes portions of the manual for GraphPad Prism that can help you learn statistics. First, review the meaning of [|P values] and [|confidence intervals]. Then learn how to interpret results from a [|one sample //t// test].
 * Learn more:**


 * Review your data:** ||


 * Mean || 8.00 ||
 * SD || 18.31 ||
 * SEM || 4.09 ||
 * N || 20 ||

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=Interpreting results: Mean, geometric mean and median = The graph shows one hundred values sampled from a population that follows a lognormal distribution. The left panel plots the data on a linear (ordinary) axis. Most of the data points are piled up at the bottom of the graph, where you can't really see them. The right panel plots the data with a logarithmic scale on the Y axis. On a log axis, the distribution appears symmetrical. The median and geometric mean are near the center of the data cluster (on a log scale) but the mean is much higher, being pulled up by some very large values. Why is there no 'geometric median'? you would compute such a value by converting all the data to logarithms, find their median, and then take the antilog of that median. The result would be identical to the median of the actual data, since the median works by finding percentiles (ranks) and not by manipulating the raw data.

Trimmed and Winsorized means
The idea of trimmed or Winsorized means is to not let the largest and smallest values have much impact. Before calculating a trimmed or Winsorized mean, you first have to choose how many of the largest and smallest values to ignore or down weight. If you set K to 1, the largest and smallest values are treated differently. If you set K to 2, then the two largest and two smallest values are treated differently. K must be set in advance. Sometimes K is set to 1, other times to some small fraction of the number of values, so K is larger when you have lots of data. To compute a trimmed mean, simply delete the K smallest and K largest observations, and compute the mean of the remaining data. To compute a Winsorized mean, replace the K smallest values with the value at the K+1 position, and replace the k largest values with the value at the N-K-1 position. Then take the mean of the data. . The advantage of trimmed and Winsorized means is that they are not influenced by one (or a few) very high or low values. Prism does not compute these values.

Harmonic mean
To compute the harmonic mean, first transform all the values to their reciprocals. Then take the mean of those reciprocals. The harmonic mean is the reciprocal of that mean. If the values are all positive, larger numbers effectively get less weight than lower numbers. The harmonic means is not often used in biology, and is not computed by Prism.

Mode
The mode is the value that occurs most commonly. It is not useful with measured values assessed with at least several digits of accuracy, as most values will be unique. It can be useful with variables that can only have integer values. While the mode is often included in lists like this, the mode doesn't always assess the center of a distribution. Imagine a medical survey where one of the questions is "How many times have you had surgery?" In many populations, the most common answer will be zero, so that is the mode. In this case, some values will be higher than the mode, but none lower, so the mode is not a way to quantify the center of the distribution.
 * URL of this page:** @http://www.graphpad.com/guides/prism/6/statistics/index.htm?stat_means_medians_and_more.htm

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