# Stats Test 1

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1. Statistics
The collection, organization, and interpretation of data for the purposes of summarization (descriptive statistics) pool drawing conclusions about populations based on samples (inferential statistics)
2. Population
A collection of objects together with a certain characteristic; precisely defined collection of values
3. Sample
Part of a population
4. Inference
Decision making based on samples drawn from populations
5. Random sample
Each and every member of the population has an equal chance of being selected
6. Internal validity
The certainty that the observations in our sample group are accurate measurements (something that is not internally valid doesn't actually change the characteristic being observed)
7. External validity
The certainty that the methods and presence of the researcher is not affecting what is being studied
8. Valid random sample
A random sample that is both internally and externally valid
9. The arithmetic mean or average value of a population
10. Sample average is approximately equal to the population average
11. Mean
Sum of all values divided by the number of values
12. Median
The middle value when data is ordered from lowest to highest

*if there are two middle values, we average the two
13. Mode
The most frequently occurring observation

*There can be no mode or multiple modes
14. Modal class
The mode for grouped data
15. Range
The difference between the highest and lowest value in the data set
16. Standard deviation
A form of average distance from the mean

17. Working backward
If we know the percentage of data between 0 and z, we look up this area (in decimal form) in the table and determine the closest z value (choose higher value if midway)
 Author: hayleyjo2 ID: 136908 Card Set: Stats Test 1 Updated: 2012-02-22 05:22:47 Tags: Statistics Folders: Description: Elementary Statistics ch 1, 2, 4 Show Answers: