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Prob & Stat Prep
Question | Answer |
---|---|
Statistics | The science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data. |
How are statistics used in everyday life? | 1. In fields of human endeavor - sports and public health 2. To analyze the results of a survey 3. As a tool in scientific research to make decisions based on controlled experiments. 4. Operations research, quality control estimation, and predictions |
Reasons to study statistics. | 1. To be able to understand statistical studies. 2. To be able to conduct research, design experiments, make predictions, and communicate results. 3. To become better consumers. |
Variable | A characteristic or attribute that can assume different values. |
Data | The values the variable assume |
Random Variables | Variable whose values are determined by chance |
Data Set | A collection of data values |
Data Value (Datum) | Each value of the data set |
Probability | The chance of an event occurring |
Population | Consists of all subjects that are being studied |
Sample | A group of subjects selected from a population |
Descriptive Statistics | Consists of the collection, organization, summarization, and presentation of data. |
Inferential Statistics | Consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables,and making predictions. |
Quantitative Variables | Numerical and can be ordered and ranked |
Discrete Variables | Variables that assume values that can be counted. |
Continuous Variables | Variables that can assume an infinite amount of values between any two specific values. (Usually obtained by measuring - fractions or decimals) |
Find the boundaries: .43 sec | .425 - .435 seconds |
Nominal Level of Measurement | Classifies data into mutually exclusive (non-overlapping) exhausting categories in which no order or ranking can be imposed on the data. |
Ordinal Level of Measurement | Classifies data into categories that can be ranked; however, precise differences between the ranks do exist. |
Interval Level of Measurement | Ranks data and precise differences between units of measure do exist;however, there is no meaningful. |
Ratio Level of Measurement | Possesses all the characteristics of the interval measurement and there exists a true zero. |
What are the two purposes of data collection? | 1. To describe situations or events 2. To help people make better decisions before acting |
3 Ways to Collect Data | Surveys, Mailed Questionnaire, Personal Interview |
Telephone Surveys | Advantage-Less costly,people can be more candid, not face to face. Disadvantages- Not all people can be surveyed, may not be home,unlisted, or cell phones. |
Mailed Questionnaire | Advantages - can cover a wider geographic area, less expensive to conduct, respondents can remain anonymous. Disadvantages - low number of responses |
Personal Interview | Advantages- can obtain in-depth response. Disadvantages- Interviewers need to be trained, more costly, interviewer may be biased, may not be a good sampling of people interviewed. |
Random Sampling | A sampling technique where you randomly select a group of subjects for study from a larger group. |
Systematic Sampling | A sampling technique where you take a random sample of the population by using every kth variable. |
Stratified Sampling | A sampling technique where you take samples from each stratum or sub-group of a population. |
Cluster Sampling | A sampling technique where the entire population is divided into groups, or clusters, and a random sample of these clusters are selected. |
Sequential Sampling | used in quality control--successive units taken form the production line and sampled to ensure the product meets the standards |
Double Sampling | A large population is given a questionnaire to see who meets the requirements for the study. After reviewing the questionnaire a smaller population is defined and a sample is chosen from this population. |
Things that make a survey question bad | 1. Asking biased questions 2. Using confusing words 3. Asking double barreled questions 4. Using double negatives in a question 5. Ordering questions improperly |
Qualitative Variables | Variables that can be placed into distinct categories(characteristics not numbers) |