1.2: The Nature of Data

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# 1.2: The Nature of Data - PowerPoint PPT Presentation

CHS Statistics. 1.2: The Nature of Data. Objective: To understand the different types of data. Data. Data ( plural ) – observations (such as measurements, genders, and survey responses) that have been collected Datum ( singular )

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CHS Statistics

### 1.2: The Nature of Data

Objective: To understand the different types of data

Data
• Data (plural)– observations (such as measurements, genders, and survey responses) that have been collected
• Datum (singular)
• Sometimes used to find statistics if the context of the data is randomly selected and/or representative of the population
Parameter vs. Statistic
• Parameter – a numerical measurement describing some characteristic of a population
• Statistic – a numerical measurement describing some characteristic of a sample
Parameter vs. Statistic – YOU DECIDE!
• A recent survey of a sample of MBAs reported that the average salary for an employee with an MBA is more than \$82,000.
• Starting salaries for the 667 MBA graduates for the University Of Chicago Graduate School Of Business increased 8.5% from the previous year.
• In a random check of a sample of retail stores, the Food and Drug Administration found that 34% of the stores were not storing fish at the proper temperature.
• When Lincoln was first elected to the presidency, he received 39.82% of the 1,865,908 votes cast.
Two Types of Data
• Quantitative Data – values that answer questions about the quantity or amount (with units) of what is being measured.
• Examples: income (\$), height (inches), weight (pounds)
• Categorical Data – (qualitative data) can be separated into different categories that are often distinguished by some nonnumeric characteristic
• Examples: sex, race, ethnicity, zip codes
• Wait? Hold up! Did I just see a zip codes as categorical data? I thought they were numbers…
Categorical vs. Quantitative - You Decide!
• Length of a song
• Responses in an opinion poll
• Telephone Number
• The genders (male/female) of college graduates
Discrete vs. Continuous Data
• Discrete Data– result when a number of possible values is either a finite number or a “countable” number (dealing with counts)
• Example: the number of students with blonde hair
• Continuous Data – result from infinitely many possible values that correspond to some continuous scale that covers a range of values without gaps, interruptions, or jumps (often times has units of measure attached)
• Example: the amount of rainfall in Zelienople this past month
Discrete vs. Continuous Data – YOU DECIDE!
• X represents the number of motorcycle accidents in one year in California.
• x represents the length of time it takes to get to work.
• x represents the volume of blood drawn for a blood test.
• x represents the number of rainy days in the month of July in Orlando, Florida.
• x represents the amount of snow (in inches) that fell in Nome, Alaska last winter.
Levels of Measurement
• Nominal – characterized by data that consist of names, labels, or categories only
• The data cannot be arranged in an ordering scheme (such as high to low)
• Example: survey responses of yes, no, and undecided
• Ordinal – can be arranged in some order, but the differences between the data values either cannot be determined or are meaningless
• Example: grade letters (A, B, C, D, F); movie ratings (1, 2, 3, 4, 5) – while you can find the difference between the ratings, it is meaningless. The difference of 1 or 2 is meaningless, because it cannot be compared to other similar differences.
Levels of Measurement (continued)
• Interval – similar to the ordinal level, but the difference between any two data values is meaningful. However, there is no natural zero starting point (where none of the quantity is present).
• Example: temperatures (while 0° F seems like a good starting point, it isn't necessarily)
• Ratio –similar to the interval, but has a natural zero starting point (where zero indicates none of the quantity is present)
• Differences and ratios are meaningful
• Example: weights of adult humans, prices of jeans
Levels of Measurement – YOU DECIDE!
• Body temperature in degrees Fahrenheit of a swimmer
• Collection of phone numbers
• Final standing for the football Northeastern Conference
• Heart rate (beats per minute) of an athlete.
1.2 Assignment

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