Chp.1 Def. Flashcards
(55 cards)
Statistics
is the science of collecting, organizing, summarizing, and analyzing information to draw conclusions or answer questions. In addition, statistics is about providing a measure of confidence in any conclusions.
population
the entire group to be studied
individual
is a person or object that is a member of the population being studied.
sample
is a subset of the population that is being studied
statistic
numerical summary of a sample
Descriptive statistics
- consist of organizing and summarizing data.
- Also describes data through numerical summaries, tables, and graphs.
Inferential statistics
Uses methods that take a result from a sample, extend it to the population, and measure the reliability of the result.
Parameter
numerical summary of a population
Variables
characteristics of the individuals within the population .
quantitative variables
values of a quantitative variable can be added or subtracted and provide meaningful results.
Nominal level of measurement
- the numbers in the variable are used only to classify the data.
- In this level of measurement, words, letters, and alpha-numeric symbols can be used.
Qualitative variables
allow for classification of individuals based on some attribute or characteristic.
Discrete variable
-is a quantitative variable that has either a finite number of possible values or a countable number of possible values.
Countable
- the values result from counting, such as 0,1,2,3 and so on…
- Discrete variable cannot take on every possible value between any two possible values.
Continuous variable
- is a quantitative variable that has an infinite number of possible values that are not countable.
- May take on every possible value between any two values.
If you count to get the value of a quantitative variable it is?
Discrete
If you measure to get the value of a quantitative variable, it is?
Continuous
Data
specific values of the variables
Ordinal level of measurement
- depicts some ordered relationship among the variable’s observations.
- Example: student 1 has a 100 percent on a test (rank1) then the next would be 92 percent 9 (rank 2) then third highest grade was a 81 percent (rank 3rd) and so on…
- ordering of the measurements.
interval level of measurement
- Classifies and orders the measurements, but also specifies that the distance between each interval on the scale are equivalent along the scale from low interval to high interval.
- Example: (level of measurement of temperature in centigrade) ===> the distance between 94 degrees C and 96 degrees C is the same as the distance between 100 degrees C and 102 degrees C.
Ratio level of measurement
In this level of measurement, the observations, in addition to having equal intervals, can have a value of zero as well.
observational study
- measures the value of the response variable without attempting to influence the value of either the response or explanatory variables.
- That is, in an observational study, the researcher observes the behavior of the individuals without trying to influence the outcome of the study.
designed experiment
if a researcher assigns the individuals in a study to a certain group, intentionally changes the value of an explanatory variable, and then records the value of the response variable for each group.
Confounding
occurs when the effects of two or more explanatory variables are not separated.