1. Introduction to Statistics
Packet #18
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2. Introduction Statistics Goals of Statistics
The mathematics of the collection, organization and interpretation of numerical data.
Especially the analysis of population characteristics by inference from sampling
Goals of Statistics
Describe what is happening now
Determining the probability of what may happen in the future
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3. Vocabulary I Population Sample The entire group of interest
A random group taken from the population
A smaller representation of the population
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4. Vocabulary II Properties of Scales of Measurement
In order to perform a statistical procedure, one must first measure something
Measurement scale, temperature for example, have different properties
Magnitude
The ability to know if one score is greater than, less than, or equal to another
Equal Intervals
Magnitude is represented by a unit of measurement that is the same no matter where it falls on the scale
Absolute Zero
Scale has a point that is equal to zero or a point where there is no score
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5. Vocabulary III Scales of Measurement
Ratio Scale
Any scale of measurement possessing magnitude, equal intervals and an absolute zero
Weight
Height
Interval Scale
Any scale of measurement possessing magnitude and equal zero but NO absolute zero
Temperature*
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6. Vocabulary IV Scales of Measurement
Ordinal Scale
Any scale that reflects only magnitude but does not contain equal intervals or an absolute zero
Ratings
Class rank order
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7. True Experiment
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8. True Experiment
The investigator attempts to determine if changes in one variable produce changes in another.
Three requirements
Must randomly divide to get two groups
Manipulate some variable
Measure the dependent variable
Statistics is used to determine the validity of the data that is gathered.
Applies for both true experiments and observational studies
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9. Correlational Study
A type of observation where the relationship between two variables is inferred
Measure two variables
Calculate the relationship
A correlational study may be considered to be a true experiment.
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10. Branches of Statistics
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11. Descriptive Statistics
Analysis is conducted to describe the obtained data.
Makes large amounts of data easy to understand
Use of numerical data to describe a phenomena
An observable fact or event
Examples
Baseball/Softball batting average
Industry production
Government deficits
Number of children in a each family along a city block
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12. Numerical Statistics Numbers, numbers and more numbers!
Clearly, some numbers are more meaningful than others
Buy vehicle #1 for $1
Buy Vehicle #2 for $1000
The mean (average) of the two prices will be an important statistic
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13. Pictorial Statistics
Taking numerical data and presenting it in pictures and/or graphs
Visual displays (graphs) are the easiest presentation
Why?
Vision may be a human’s best ability to understand material
Complex information is better memorized visually
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14. Inferential Statistics
Analysis is conducted to make inferences (derived as a conclusion from facts or premises) about a population using data obtained from the sample
Uses descriptive and probability theory to make judgments about reality
Previously covered
Did “this” cause “that?”
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15. Statistics and The Scientific Method
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16. The Relation Hypothesis Recording & Analyzing data Probability
Allows the investigation of the independent variable on the dependent variable
True Experiment
Recording & Analyzing data
Statistics provides an analysis of data that determines whether your data is accurate
Probability
One of the most familiar uses of statistics is to determine the chance of some occurrence.
If…then statement (Hypothesis)
Example
Flipping a coin to see how many times it lands on heads or tails
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