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A descriptive measure of a sample |
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statistic |
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method of organizing, summarizing, and presenting data |
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descriptive statistics |
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The group of all items of interest |
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population |
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the process of making an estimate. prediction, or decision about a population based on sample data |
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statistical inference |
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a set of data drawn from a population |
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sample |
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the data can be arranged in order & differences b/w data values are meaningful |
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interval scale |
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the data consists of names, labels, or categories. There are no criteria for ordering the data from smallest to largest |
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nominal scale |
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the data can be arranged in order & both & ratios b/w data values are meaningful. Also data has a true, absolute zero. |
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ratio scale |
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the data can be arranged in order. However, differences b/w data values either can;t be determined or are meaningless |
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ordinal scale |
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The Requirements of a Random Sample |
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1. Each indiv. in population of interest must have an equal probability of being of being included in the sample 2. They all have equal chance of being picked |
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Divide the entire population into pre-existing segments or clusters. The clusters are often geographic. Make a random selection of clusters. Include every member of each selected cluster in the sample. |
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Cluster sampling |
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Create a sample by using data from population members that are readily available. |
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Convenience Sampling |
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A simple random sample of n measurements from a population is a subset of the population selected in a
manner such that every sample of size n from the population has an equal chance of being selected. |
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Simple Random Sampling |
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Divide the entire population into distinct subgroups called strata. The strata are based on a specific characteristic such as age, income, education level, and so on. All members of a stratum share the specific characteristic. Draw random samples from each stratum. |
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Stratified Sample |
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Number all members of the population sequentially. Then, from a starting point selected at random, include every kth member of the population in the sample. |
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Systematic sampling |
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A variable that describes an individual by placing the individual into a category or group, such as male or female. |
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Qualitative variable |
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A quantitative variable has a value or numerical measurement for which operations such as addition or averaging make sense. |
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Quantitative variable |
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numerical measure that describes an aspect of a population. |
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Parameter |
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Given a random sample of 9 skiers at Vail:18, 25, 32,16, 41, 52, 29, 58, 23Give the 5 number summary values w labelsX= |
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XMin= 16; Q1= 20.5; Med (Q2)= 29; Q3= 46.5; Xmax=58 Age of skiers |
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What is IQR and how do you find it? |
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Interquartile RangeQ3-Q1= 20.5 |
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How do you find the sample mean? |
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Summation of X divided by n
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How do you find the median? |
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Order the data and then find the physical middle; Position= (n+1)/2 |
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How do you find the mode? |
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it is the most frequent |
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How to find Weighted Mean |
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Summation (Weight x Data) / Summation(Weight) |
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How do you find the Range? |
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Xmax - Xmin |
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How do you find the sample mean? |
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Summation(X) / n |
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How do you find the sample standard deviation? |
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fill in |
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Computational Formula (Standard Deviation) |
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fill in |
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Population Standard Deviation |
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fill in |
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Sample Variance |
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fill in |
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Population Variance |
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fill |
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Sample Mean for Grouped Data |
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fill |
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