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beginning Statistics
reflection on descriptive statistics
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Recommended: beginning Statistics
Chapter 12 introduces the reader to the true definition of statistics, without scaring them half to death. The book breaks statistics down in two parts: descriptive and inferential. The type that is dealt with in this chapter is descriptive statistics. The simple definition of descriptive statistics are that they are just numbers in different forms, for example, percentages, numerals, fractions, and decimals. The book gives an example of a grade point average being a descriptive statistic. It is becoming increasingly important for classroom teachers to be able to understand and interpret statistics because of increasing calls for acountablity. Being able understand various types of statistics, there uses and limitations, will put the educator who does at an advantage. Instead of just averaging grades, there are important questions that every educator should want to know the answers to regarding their classroom. Questions like, how many people are above average and how many scored above the cutoff passing score, are questions that can't be answered without some working knowledge of statistics. The bar graph explanation was pretty clear in the chapter, but that might be just because it's the most frequently used graph to convey statistical data. Everyone is familiar with the bar graph, but when it comes down to frequency polygons things get a little fuzzy. Chapter 13 explains how distributions can have the same values for the mode, median, and mean but are different in the way the scores are spread out. The variability estimate helps determine how compressed or expanded the distributions are. The range is the easiest way to estimate variability and its determined from subtracting the lowest score from the highest score. In the case of the range, things can get thrown off if an extreme score is present. One way of preventing this from happening is to use the semi-interquartile range. This score is determined by taking the middle 50% of the scores in a distribution. The upper 25% and the lower 25% are not entered into its final computation. Standard deviation is an estimate of variability that accompanies the mean in describing a distribution. You are taking a look at each distribution to see how far away each score deviates from the mean. The normal distribution is a type of symmetrical distribution that is mathematically determined and has fixed properties. It is basically used as a model to base statistical decisions. These are methods that can most definitely be used in the classroom when analyzing data.
Next this information was then turned into a box and wicker plot for more in-depth interrogation of the data.
The normal distribution is very utilizable because of the central limit theorem, which states that, under mild conditions, the mean of many arbitrary variables independently drawn from the same distribution is distributed approximately customarily, irrespective of the form of the pristine distribution: physical quantities that are expected to be the sum of many independent processes (such as quantification errors) often have a distribution very proximate to the Gaussian. Moreover, many results and methods (such as propagation of dubiousness and least squares parameter fitting) can be derived analytically in explicit form when the germane variables are normally distributed.
Standardized testing assesses students, teachers, and the school itself, which puts a great deal of pressure on the students. High scores show that the school is effective in teaching students, while low test scores make teachers and schools look as though they are not teaching the students properly. This is not always the case. There are teachers who do teach students what they need to know to pass the test, but their students are still unprepared. Although teachers try to improve instruction, student performance is still variable to other factors that the school cannot control.
The final chapter of this book encourages people to be critical when taking in statistics. Someone taking a critical approach to statistics tries assessing statistics by asking questions and researching the origins of a statistic when that information is not provided. The book ends by encouraging readers to know the limitations of statistics and understand how statistics are
There are two histograms, showing information on GPA, and showing information on final grade. Histograms are commonly used with interval or ratio level data (Corty, 2007). The data in the GPA is distributed and slightly skewed to the right, which means it has a positive skew and has a peaked distribution. The final histogram also has a leptokurtic frequency distribution, but is skewed to the left meaning this has a negative skew.
Standard Deviation is a measure about how spreads the numbers are. It describes the dispersion of a data set from its mean. If the dispersion of the data set is higher from the mean value, then the deviation is also higher. It is expressed as the Greek letter Sigma (σ).
...will fall within the first standard deviation, 95% within the first two standard deviations, and 99.7% will fall within the first three standard deviations of the mean. The Empirical Rule is used in statistics for showing final outcomes. After a standard deviation is found, and before exact data can be collected, this rule can be used as an estimate to the outcome of the new data. This probability can be used for gathering data that may be time consuming, or even impossible to found. When the mean equals the median and the values cluster around the mean and median, producing a bell-shaped distribution, then we can use the empirical rule to examine the variability. In this bell-shaped data set, we can calculate the mean and the standard deviation. The mean means the average value of the set of data. The standard deviation means the average scatter around the mean.
The first table was titled Other Measures. It provided information on the sample size, minimum, maximum, first quartile, third quartile, given percentage, and value of percentile. These values are used to compute range and interquartile range in the measures of dispersion. The last table shows the mean plus or minus 1, 2, or 3 times the standard deviation and offers details on how many values fall within the ranges created by those calculations.
It establishes how far they have deviated from the mean in either direction. It gives us detail about the proportion of the distribution are -1 and +1 from the standard deviation, as well two standard deviations from the mean. This can be useful in measuring differences within a group of participants. For example, in a class where the mean is 50% for both boys and girls, looking at the standard deviation can show how much each gender deviated from the mean and can highlight the spread of scores. This can be a more useful
Reliability (extent to which a test yields consistent results, as assessed by the consistency of scores on two halves of the test, on alternate forms of the test or on retesting)- Comparing test scores to those of the standardizing group still won't tell us much about the individual unless the test has reliability.
In evaluating statistical data one thing to consider is the measure that is used. By understanding the different statistical measurement tools and how they differ from one another, it is possible to judge whether a statistical graph can be accepted at face value. A good example is using the mean to depict averages. This was demonstrated by using the mean as a measure of determining the distribution of incomes. The mean income depicted was, $70,000 per year. At face value, it looks as though the sample population enjoys a rather high income. However, upon seeing individual salaries, it becomes obvious that only a few salaries are responsible for the high average income as depicted by the mean. The majority of the salaries were well under the $70,000 average. Therefore, the mean distributed income of $70,000 was at best misleading. By also looking at the median and mode measures of the income distributions, one has a clearer picture of the actual income distributions. Because this data contained extreme values, a standard deviation curve would have given better representation of salary distribution and would have highlighted the salaries at the high level and how they skewed the mean value.
Based on the total means, the values of A and B were computed from the total means and standard deviations from each trait group.
During statistics, a standard score indicate how several standard deviations an observation or else datum be exceeding otherwise below the mean. It is a dimensionless quantity resultant through subtracting the population mean since a being raw score also then separating the difference through the population standard deviation. Standard deviation is the part of measurement of the z-score. It allows association of clarification from dissimilar normal distributions, which is made normally in examine.
Warner, B. C., & Meehan, A. M. (2001, September). Microsoft Excel as a Tool for Teaching Basic Statistics. Retrieved April 6, 2005, from EBSCOhost database: http://search.epnet.com/login.aspx?direct=true&db=qeh&an=BEDI01029542.
One of the biggest, if not the biggest, challenge you face going through school is the standardized tests you must take at the end of the year, every year, starting in third grade. You must past these tests in order to move on to the next grade, or you keep taking them until you pass. A big question many people ask is how are these tests beneficial to real life education? The student, the teachers, the principal and the school districts are all judged based on the average scores on these tests. So, if you put that into perspective, our schools are being judged based on test results when the tests themselves are not ideal education. They are not a part of the ideal education that the kids actually remember and help them succeed in their everyday life. These standardized tests scores are not a good indication of a school’s competency because it does not prove knowledge or understanding. They take light away from real life educational understanding and put the emphasis on passing a silly test.