vocab Flashcards
Individuals
One data point in a survey
Variable
Something that can change in an experiment. Sometimes the variables are not obvious and can cause confusing results.
Categorical variable
A variable that can fall into one of multiple categories, as opposed to a quantitative one.
Quantitative variable
A variable with a number value that holds significance (i.e although a zip code is a number, the numerical value is unimportant, so it is categorical)
Discrete variables
A type of data that can only come at set values. For example, number of pairs of socks can only be a whole number.
Continuous
A type of data that can fall anywhere on a spectrum. For example, temperature in degrees Celsius isn’t restricted to any type of discrete step, it can be any value.
Univariate data
Data with one variable associated. For example, when asking students how many socks they have, the only variable associated with that student is their number of socks.
Bivariate data
Data with two variable associated. For example, a survey that asks students both how many socks they have and how many shoes they have is collecting bivariate data.
Population
The group of people of objects that a survey collects data about. For an interview asking students at Grady how many socks they have, the population is the students at Grady.
Sample
A sample is a number of individuals taken from a population that should represent that population fairly well. For example, instead of asking every student at Grady how many socks they have, one could instead take a sample of all the students, and only ask 20 random students from each grade.
Census
A census is a survey which gathers data from every individual in a population. The goal is to get the most accurate data as no extrapolation is necessary. A good example is the US Census.
Distribution
The distribution is how the data are spread out. It is easiest to understand when graphed on a dot plot, bar chart, or histogram. The distribution of number of socks the students at Grady have would look quite different from the distribution of the distribution of the incomes of families in the United States.
Inference
An inference is an extrapolation from a sample to a whole population. For example, if in a sample of 80 Grady students, 78% reported having more than 20 pairs of socks, one could infer that a similar percentage of the whole population of Grady students would have more than 20 pairs of socks.
Frequency Table
A table which matches an occurrence with the number of times it occurred.
Relative Frequency Table
A relative frequency table matches on occurrence with the percent of times it occurred in relation to the total number of samples.
Roundoff error
The error created when values are rounded off at a certain point. For example, if 8 categories each had the same frequency (12.5%), but that was rounded to the nearest whole number, one might find that the total comes out to be 13% * 8 or 104%.
Pie chart
A visual chart showing how different categories contribute to a whole. Shown as a circle split into segments whose internal angles are determined by the relative frequency of that segment’s corresponding category.
Bar graph
A graph which represents data by using bars of different heights or lengths.
Two-way table
A way of organizing data in a table so that each cell has a number in it which is the number of people who correspond with that cell’s location. For example, a two-way table could have the countries UK and US along the top, and preferred superpowers of students along the left. Each cell would house the number of students from that country who preferred that superpower.
