Math 251 Stats Exam 1 Questions And Correct Answers

MATH 251 STATS EXAM 1 QUESTIONS
AND CORRECT ANSWERS
Statistics are the study of ________________ - ANSWERS-data
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A 'statistic' is - ANSWERS-a measurement that describes a sample
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2 types of statistics - ANSWERS-descriptive and inferential
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Descriptive stats - ANSWERS- 5f 5f 5f


used to organize and summarize data. often uses pie charts and averages. these are
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facts
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Inferential stats - ANSWERS- 5f 5f 5f


used to make predictions, generalizations or assumptions and conclusions. requires
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use of probability to measure confidence in them. These are educated guesses and
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we measure their reliability using probabilities.
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Anecdotal claim - ANSWERS- 5f 5f 5f


a conclusion based on very little data. (often one persons account)
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Population - ANSWERS-complete set of information; everything. not biased. (N)
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Parameters - ANSWERS- 5f 5f


measurements that describe populations, usually denoted by greek letters or with N. 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f 5f




sample - ANSWERS-a subset or portion of the population. may be biased. (n)
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Statistics - ANSWERS- 5f 5f


measurements that describe a sample, usually denoted by english letters 5f 5f 5f 5f 5f 5f 5f 5f 5f




You should ___________ statistics and ____________ parameters - ANSWERS-
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question, accept 5f




(Random) variable - ANSWERS- 5f 5f 5f


any characteristic that varies from individual to individual within a population, typicall
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y denoted by capital letters. knowing the type of variable will help you choose the ap
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propriate graph, formula, or test method. 5f 5f 5f 5f 5f




Data - ANSWERS-actual values of a variable
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Qualitative/ Categorical Variables - ANSWERS- 5f 5f 5f 5f


attributes, categories, or characteristics that are not naturally numeric like ethnicity, d
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egree level of education and zip code.
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typically use pie charts and % 5f 5f 5f 5f 5f




Quantitative/ Numeric Variables - ANSWERS- 5f 5f 5f 5f


values that are numeric like age, GPA, and temperature. typically use averages
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, Discrete (Quantitative) variable - ANSWERS- 5f 5f 5f 5f


variables that have a finite or a countable number of outcomes. often counts.
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write possible values in a list: x=1,2,3...
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*has gaps 5f


Examples: # of tornadoes in a year, # of ppl with attached earlobes, grade point in C
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Continuous (Quantitative) variable - ANSWERS- 5f 5f 5f 5f


variables that have an infinite number of outcomes which are usually measured and r
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ounded and fall on some interval. 5f 5f 5f 5f 5f 5f


write possible values in interval notation: x E [0,100)
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Examples: length of newborn in cm, # of calories in a sandwich, GPA
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Simple Random Sample (SRS) - ANSWERS-
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when every possible sample of size n out of a population of N has an equally likely c
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hance of occurring. Least likely to be biased.
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Example: write names on pieces of paper and draw from a hat
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Frame - ANSWERS- 5f 5f


a list of all the individuals within the population required for a simple random sample
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Systematic (random) sampling - ANSWERS- 5f 5f 5f 5f


select some random starting point and then select every n'th individual in the populati
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on.

When to use systematic sampling - ANSWERS-when you don't have a frame
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Stratified (random) sampling - ANSWERS-Some of every group.
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separate groups by strata/characteristic, then choose SRS from each strata
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should be proportionate to population
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Cluster (random) sampling - ANSWERS-Collect all of some groups.
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divide population into clusters (usually based on proximity). choose random clusters
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and include all people within that cluster
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Multistage sampling - ANSWERS- 5f 5f 5f


using a combo of SRS, stratified, systematic, and/or cluster sampling. Many large sc
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ale samples are done using this method. Mixture of both cluster and stratified.
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Convenience sampling - ANSWERS-choosing individuals who are easiest to reach 5f 5f 5f 5f 5f 5f 5f 5f 5f


example: asking around and self-selecting surveys. 5f 5f 5f 5f 5f


little statistical validity because the design is poor.
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**NOT RANDOM 5f




4 levels of measurement - ANSWERS-1. Nominal
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2. Ordinal
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3. Interval
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4. Ratio
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