Stats Vocab

data

information about the characteristics of a group of individuals

Categorical variable

describes a particular characteristic which can be divided into categories

ex) gender (categories are male and female)

Quantitative Variable

describes a characteristic which has a numerical value that can be counted or measured

Population

an entire collection of individuals about which we want to draw conclusions

Census

the collection of information from the whole population

Parameter

a numerical quantity measuring some aspect of a population

sample

a group of individuals selected from a population

survey

the collection of information from a sample

Statistic

a quantity calculated from data gathered from a sample, usually used to estimate a population parameter

Sampling error

occurs when a characteristic of a sample differs from that of the whole population

Measurement error

refers to inaccuracies in measurement at the data collection stage (ie. recording someone’s height to the nearest cm vs. the exact height

Coverage errors

Occur when a sample does not truly reflect the population we are trying to find information about

Non-response errors

occur when a large number of people selected for the survey choose not to respond to it

Simple random sampling

when each member of the population has the same chance of being selected

systematic sampling

picking a sample with a selection criteria

Convenience Sampling

when the experimenter picks the sample based on it being easy to collect or more likely to respond

Stratified Sampling and Quota Sampling

when the population can be divided into subgroups and then selecting a proportional amount of people from each subgroup

Descrete quantitative variable

takes exact number values

ex) number of players in a game of soccer or number of apricots in a tree

Continuous quantitative variable

can take any numerical value within a certain range (result of measuring)

ex) the distance of each hit in baseball or the times taken to run a 100m race

Relative frequency

the frequency ÷ the total number of recorded values

Outliers

data values that are either much larger or much smaller than the general body of the data

Modal Class

the class with the highest frequency