Quote of the DayOh, people can come up with statistics to prove anything. 14% of people know that. ---Homer Simpson What are Statistics?
Chapter 1:The Nature ofProbability and Statistics Section 1: Descriptive and Inferential Statistics
Stats in Daily Life Of the people in the US, 14% said they feel happiest in June, and 14% said they feel happiest in December. The average in-state college tuition and fees for 4-year pubic college is $5,836. Every day in the US about 120 golfers claim that they made a hole-in-one. 4 out of 5 doctors leaves one doctor.- Chevy Chase
What is Statistics? The science of conducting studies to collect, organize, summarize, analyze and draw conclusions from data.
What is Data? The values that the variables can assume. A collection of values forms a Data Set Each Value in the data set is called: Data Value or Datum
What is a variable? A characteristic or attribute that can assume different values.
Types of Statistics1. Descriptive Statistics Consists of the collection, organization, summarization, and presentation of data Ex: Government Census Taken every ten years Describes average income, family size, etc.. What does this mean? Basically used to describe a situation.
Types of Statistics2. Inferential Statistics Consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions. Ex: Winning the lottery 1 in a million What does this mean ? Used to predict the outcome of an event.
What is the difference between aPopulation and a Sample? Population- consists of all subjects that are being studied. Sample- is a group selected from a population.
Section 2: Types of Variables Qualitative Variables: Variables that can be placed into distinct categories, according to some characteristic or attribute. Ex: Gender, Eye color, Geographic Location
2 Types of Variables Quantitative Variables: Variables that are numerical and can be ordered or ranked. Ex: Age, height, weight, body temp Classified by two groups Discrete Variables Continuous Variables
Measurement Scale Used to categorize, count, or measure variables. Types: Nominal Ordinal Interval Ratio
Nominal Level of Measurement Classifies data into mutually exclusive, exhausting categories in which no order or ranking can be imposed on the data. Ex: Male/Female Single/Married/Divorced/Widowed/Separated Democratic/Republican
Ordinal Level of Measurement Classifies data into categories that can be ranked; however, precise differences between the ranks do not exist. Ex: Letter Grades (A, B, C, D, F) 1st, 2nd, 3rd, etc Small, Medium, Large Freshman, Sophomores, Juniors, Seniors
Interval Level of Measurement Ranks data, and precise differences between units of measures do exist: however, there is no meaningful zero. Ex: Temperature: 72°F and 73°F, difference of 1°F, but 0°F does not mean no heat present IQ: 109 and 110, difference of 1 point, but 0 does not mean there is no intelligence.
Ratio Level of Measurement Possesses all the characteristics of interval measurements, and there exists a true zero. In addition, true ratios exists when the same variables is measured on two different members of the population. Ex: Salary Time Age
Section 4: 2 Types of Studies Observational Study Researchers merely observe what is happening or what has happened in the past Try to draw conclusions based on these observations. Ex: studying creatures in the wild “Meerkat Manor”
Section 4: 2 Types of Studies Experimental study Researchers manipulate one of the variables Tries to determine how to the manipulation influences other variables. Ex: New medication and placebos
Statistical Studies include…. Independent variables In an experimental study is the one that is being manipulated by the researcher. Also called: Explanatory variable Dependent variables Resultant variable Also called: Outcome variable
Misuses of Statistics Suspect Samples Too small Convenience Volunteers Changing the subject Increase of 3% Increase of $600,000
Misuses of Statistics Detached Statistics- no comparison “Works 5 times faster” “1/3 fewer calories” Implied Connection “Eating fish may help you achieve better in school”
Misuses of Statistics Misleading Graphs- Chapter 2 Faulty Survey Questions “Do you feel there should be a 4 day school week?” “Do you feel there should be a 4 day school week from 4 am to midnight?”
Section 1-6: Computers andCalculators Computer and Calculators GOOD