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Qualitative data Step-by-step explanation: can be separated into different categories that are distinguished by some nonnumeric characteristics such as gender, major classifications, political party affiliation, religious preference, marital status, and the like Presentation on theme: "Measurements in Statistics"— Presentation transcript: 1 Measurements in Statistics
2 2.1 Data Types and Levels of Measurement 3 Data Types Qualitative (or categorical) data consist of values that can be separated into different categories that are distinguished by some nonnumeric
characteristic. Quantitative data consist of values representing counts or measurements. 4 A person’s social security number 5 Types of Quantitative Data 6 The number of
1916 dimes still in circulation
7 Levels of Measurement Nominal Ordinal Interval Ratio
8 TYPES OF QUALITATIVE MEASUREMENTS 9 TYPES OF QUANTITATIVE MEASUREMENTS 10 CLASSIFY THE FOLLOWING AS TO QUALITATIVE OR QUANTITATIVE
MEASUREMENT
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14 2.2 Dealing with Errors Mistakes are the portals of discovery. 15 Two Types of Measurement Error 16 Measurement Error T = True value of the observation 17 What is random error? Caused by any factors that randomly affect measurement of the variable across the sample. Each person’s
mood can inflate or deflate their performance on any occasion. In a particular testing, some children may be in a good mood and others may be depressed. Mood may artificially inflate the scores for some children and artificially deflate the scores for others. Random error does not have consistent effects across the entire sample. If we could see all the random errors in a distribution, the sum would be zero. The important property of random error is that it adds
variability to the data but does not affect average performance for the group. 18 19 What is systematic error? 20 21 Reducing Measurement Error
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23 Is the potential error systematic or random? 24 Copyright © 2009 Pearson Education, Inc. 25
Identify at least one likely source of random errors and at least one likely source of systematic errors. You need to measure 50 meters for a sprint workout. You don’t have a tape measure, so you use a meter stick to measure the distance. You are doing a survey about alcohol use among college students. You ask students to write down how many drinks they have consumed in the last week.
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Determine the absolute and relative error. 28
Copyright © 2009 Pearson Education, Inc. 29 Avogadro’s number is the number of molecules of a substance in a quantity of the substance
measured in grams equal to its atomic weight. It can only be determined by chemistry or physics experiments. It is named after Amadeo Avogadro, who postulated in 1881 that this number is the same for all substances. Various values for this constant have been determined experimentally. Some of them are 6.02 1023, 1023, and The 1023 means that you have to move the decimal point 23 places to the right. Which of these values is the most accurate? Which of
these values is the most precise? 30 Compared to a scale that measures your height to tenths of feet, a scale that
measures your height to the nearest inch is. a. more precise and more accurate. b. less precise, but may be more accurate. c. more precise, but may be less accurate. d. less precise and less accurate. 31 Copyright © 2009
Pearson Education, Inc. Can be separated into categories that are distinguished by some nonnumeric characteristics?Qualitative variables: Variables that can be separated into different categories distinguished by some nonnumeric characteristic.
What is the collection of all measurements where some characteristics are being studied?A population is the complete collection of all elements (scores, people, measurement, and so on) to be studied. The collection is complete in the sense that it includes all subjects to be studied. A census is the collection of data from every element in a population.
Which of the following is the numerical characteristic of a sample?A statistic is a numerical description of a sample characteristic.
What do you call a number that describes a population characteristic?A parameter is a number describing a whole population (e.g., population mean), while a statistic is a number describing a sample (e.g., sample mean). The goal of quantitative research is to understand characteristics of populations by finding parameters.
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