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Chapter 1
Introduction To Statistics
Term | Definition |
---|---|
There Are 2 Types of Data | 1. Quantitative Data.. 2. Qualitative Data |
Quantitative Data | These are numbers |
Qualitative Data | These are categories. Not numbers |
There Are 2 Types of Quantitative Data | 1. Discrete Data.. 2. Continuous Data |
Discrete Data | Whole numbers. Ex: The # people on the bus |
Continuous Data | These are decimals. If data could be a decimal, it is continuous. Ex: Weight of a whale in pounds |
Population | Every individual of interest. Doesn't have to be people |
Parameter | A number that describes some aspect of the population. Computed from population |
Sample | Subgroup of population |
Statistic | A number that describes some aspect of the sample |
Levels of Measurement(4 levels) | 1. Nominal.. 2. Ordinal.. 3. Interval.. 4. Ratio |
Nominal | Categories, cannot be ordered, most basic level. Ex: brand of shoe |
Ordinal | Categories, can be ordered, cannot do math operation with. Ex: quality rating of a Choco bar(bad, okay, good) |
Interval | Numbers, no true zero. Ex: temperature, time of arrival |
Ratio | Number, there is a true zero. Ex: # people who believe in aliens, cost of a Big mac, time it takes to eat a hotdog |
Sampling Techniques | 1. Random Sample.. 2. Simple Random Sample.. 3. Cluster Sample.. 4. Stratified Sample.. 5. Systematic Sampling.. 6. Convenience Sample |
Random Sample | Every individual from a population has equal chance of being selected |
Simple Random Sample | Every possible group of individuals has an equal change of being selected |
Cluster Sample | Divide population into groups, randomly select some of the GROUPS. Ex: There are 50 states and you randomly select 25 states(our sample is everyone in those 25 states) |
Stratified Sample | Divide population into groups, randomly select INDIVIDUALS from each group. Ex: Randomly select 10 people from each of the 50 states(our sample is 500 people) |
Systematic Sampling | Order the data, pick a starting point, select every 2nd, 3rd, 4th, etc. person. Ex: number names in phonebook then start with 3rd person then pick every 4th person(Sample is person 3, 7, 11, 15) |
Convenience Sampling | Uses data that is readily available. Don't want to get data this way usually. Ex: Theo surveys his best friends |