Statistics Chapter 1- Test 1

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Statistics Chapter 1- Test 1

Statistics. Understandable Statistics

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A descriptive measure of a sample
method of organizing, summarizing, and presenting data
descriptive statistics
The group of all items of interest
the process of making an estimate. prediction, or decision about a population based on sample data
statistical inference
a set of data drawn from a population
the data can be arranged in order & differences b/w data values are meaningful
interval scale
the data consists of names, labels, or categories. There are no criteria for ordering the data from smallest to largest
nominal scale
the data can be arranged in order & both & ratios b/w data values are meaningful. Also data has a true, absolute zero.
ratio scale
the data can be arranged in order. However, differences b/w data values either can;t be determined or are meaningless
ordinal scale
The Requirements of a Random Sample
1. Each indiv. in population of interest must have an equal probability of being of being included in the sample 2. They all have equal chance of being picked
Divide the entire population into pre-existing segments or clusters. The clusters are often geographic. Make a random selection of clusters. Include every member of each selected cluster in the sample.
Cluster sampling
Create a sample by using data from population members that are readily available.
Convenience Sampling
A simple random sample of n measurements from a population is a subset of the population selected in a manner such that every sample of size n from the population has an equal chance of being selected.
Simple Random Sampling
Divide the entire population into distinct subgroups called strata. The strata are based on a specific characteristic such as age, income, education level, and so on. All members of a stratum share the specific characteristic. Draw random samples from each stratum.
Stratified Sample
Number all members of the population sequentially. Then, from a starting point selected at random, include every kth member of the population in the sample.
Systematic sampling
A variable that describes an individual by placing the individual into a category or group, such as male or female.
Qualitative variable
A quantitative variable has a value or numerical measurement for which operations such as addition or averaging make sense.
Quantitative variable
numerical measure that describes an aspect of a population.
Given a random sample of 9 skiers at Vail:18, 25, 32,16, 41, 52, 29, 58, 23Give the 5 number summary values w labelsX= 
XMin= 16;  Q1= 20.5;  Med (Q2)= 29;  Q3= 46.5;  Xmax=58 Age of skiers
What is IQR and how do you find it?
Interquartile RangeQ3-Q1= 20.5
How do you find the sample mean?
Summation of X divided by n
How do you find the median?
Order the data and then find the physical middle; Position= (n+1)/2
How do you find the mode?
it is the most frequent
How to find Weighted Mean
Summation (Weight x Data) / Summation(Weight)
How do you find the Range?
Xmax - Xmin
How do you find the sample mean?
Summation(X) / n
How do you find the sample standard deviation?
fill in
Computational Formula (Standard Deviation)
fill in
Population Standard Deviation
fill in
Sample Variance
fill in
Population Variance
Sample Mean for Grouped Data