浙江大學(xué)肖忠華語料庫-文庫吧
2025-04-25 00:34 本頁面
【正文】 speech as in writing ? Swearword in spoken BNC = 250 / 10 * 1 = 25 per million tokens ? Swearword in written BNC = 500 / 90 * 1 = 6 per million tokens – …but is this difference statistically significant? Normalized frequency ? The size of a sample may affect the level of statistical significance ? Tips for normalizing frequency data – The mon base for normalization must be parable to the sizes of the corpora ? Normalizing the spoken vs. written BNC to a mon base of 1000 tokens? ? Warning – Results obtained on an irrationally enlarged or reduced mon base are distorted Descriptive statistics ? Frequencies are a type of descriptive statistics ? Descriptive statistics are used to describe a dataset ? A group of ten students took a test and their scores are as follows – 4, 5, 6, 6, 7, 7, 7, 9, 9, 10 ? How will you report the measure of central tendency of this group of test results using a single score? The mean ? The mean is the arithmetic average ? The most mon measure of central tendency ? Can be calculated by adding all of the scores together and then dividing the sum by the number of scores (. 7) – 4+5+6+6+7+7+7+9+9+10=70/10=7 ? While the mean is a useful measure, unless we also knows how dispersed (. spread out) the scores in a dataset are, the mean can be an uncertain guide The mode and the median ? The mode is the most mon score in a set of scores – The mode in our testing example is 7, because this score occurs more frequently than any other score ? 4, 5, 6, 6, 7, 7, 7, 9, 9, 10 ? The median is the middle score of a set of scores ordered from the lowest to the highest – For an odd number of scores, the median is the central score in an ordered list – For an even number of scores, the median is the average of the two central scores ? In the above example the median is 7 (. (7+7)/2) Measure of dispersion: range ? The range is a simple way to measure the dispersion of a set of data – The difference between the highest and lowest frequencies / scores – In our testing example the range is 6 (. highest 10 – lowest 4) ? Only a poor measure of dispersion – An unusually high or low score in a dataset may make the range unreasonably large, thus giving a distorted picture of the dataset Measure of dispersion: variance ? The variance measures the distance of each score in the dataset from the mean – In our test results, the va
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