UNIT 1, ALL LESSONS VOCAB / KEY CONCEPTS

Question 1

descriptive statistics

Answer 1

summarizing and describing features of a data set without making any generalizations/conclusions about a population
› states facts and proven outcomes we already know

Question 1

inferential statistics

Answer 1

uses data from a sample/population to draw conclusions and make predictions about a larger population
› analyzes data to make predictions that we don’t know

Question 2

phases of a statistical study

Answer 2

› phase 1, data gathering: any process that gets you data (surveys, questionnaires, counting, etc.)
› phase 2, data organization and analysis: includes making graphs, charts, and tables, from data and can also include calculating stats and analyzing data looking for patterns
› phase 3, probability-based inference: the process of using data to make conclusions about a population based on a sample of that population

Question 2

statistical inference

Answer 2

process of using data to make conclusions about a population based on a sample

Question 2

statistic

Answer 2

number that describes a sample

Question 3

probability

Answer 3

mathmatical concept that measures the likelihood of an event occuring

Question 4

data

Answer 4

a bunch of facts collected together for reference and analysis

Question 4

parameter

Answer 4

a number that describes a population

Question 5

data set

Answer 5

set or collection of data

Question 6

datum

Answer 6

a bit of information / facts

Question 7

numeric/quantitative data

Answer 7

data that is used as numbers and can be sorted and calculated
› can be sorted and worked with mathematically
› presented in numbers
› can be discrete or continuous
- discrete data is gathered by counting and can be whole numbers (counted data is a form of discrete data (numbers of people, anything counted)
- continuous data is gathered by measuring and are always numerical, can be fractions or decimals of any length (measured data, is a form of continuous data (lengths, weights, volumes- anything measured)

Question 7

(non-numeric) categorical/qualitative data

Answer 7

data that is named or can be put into categories and cannot be sorted and can’t do calculations
› can be divided into groups or categories

Question 8

distribution

Answer 8

a set of numbers on a graph that shows the possible values for a variable and how often they occur
› cannot be any graph

Question 9

variable

Answer 9

a characteristic, number, or quantity that can be measured or counted, and that can take on different values (ex. age, sex, income, etc.)

Question 9

univariate data

Answer 9

a set of data that only focuses on one variable (ex. salaries of employees in a company, the number of pets in different households, length of trouts in a lake, etc.)

Question 9

unit of analysis

Answer 9

the major entity that you are analyzing in your study

Question 10

class width

Answer 10

the difference between the upper and lower class limits of a class interval (ex. class interval 163-175, class width is 175-163=12)

Question 10

constant

Answer 10

a fixed value that never changes within a given context

Question 10

bar graph

Answer 10

a visual representation of data where rectangular bars are used in a way of showing the distribution of data
› counts or percents are on the vertical axis
› categories are on the horizontal axis

Question 10

observation

Answer 10

a fact or figure we collect about a given variable

Question 10

class

Answer 10

the range of values assigned to a group of data points (ex. 0-10, 11-20, 21-30, etc.)

Question 10

class boundaries

Answer 10

the values that separate different classes (or groups) within a data set

Question 11

relative frequency

Answer 11

the ratio (fraction or proportion) of the number of times a value of the data occurs in the set of all outcomes to the total number of outcomes
› calculation: divide the frequency (the number of times a particular value for a variable has been observed to occur) of a specific category by the total number of observations
› can also be in table form- one column contains values or intervals- other column contains frequencies

Question 11

class interval

Answer 11

a range of values within a data set that are grouped together for analysis

Question 11

histogram

Answer 11

a graphical representation that displays the distribution of numerical data using rectangles › height of a rectangle (vertical axis) represents the distribution frequency of a variable (amount, or how often that variable appears) › height of bars display frequency › width of bars display intervals › has midpoints- the exact center of value of a given bin (or class interval), calculated by adding the upper and lower boundary values of that bin and dividing the sum by two)

Question 11

relative frequency histogram

Answer 11

a graph that displays the classes on the horizontal axis and the relative frequencies on the classes on the vertical axis

Question 12

frequency table

Answer 12

a list that shows how often each value occurs in a set of data

Question 12

cumulative relative frequency

Answer 12

a summary of a data set showing the relative frequency of items less than or equal to the upper-class limit of each class; tells you the percentage of data that falls within a specific category or below a specific point on the data scale › plot cumulative frequency on the vertical axis › place class boundaries or interval midpoints on the horizontal axis › classes are on the horizontal axis › cumulative frequencies are on the vertical axis

Question 13

SUMMARY 1.2 ACTIVE RECALL

Answer 13

data presented with frequencies › individual values often occur many times in a distribution › classes or intervals group data › frequency tables show frequencies for all the classes in your data histograms from frequency data › histograms are graphical interpretations of frequency data › are made up of vertical bars › height of bars display frequency › width of bars display intervals relative frequency tables › relative frequencies are included in a summary table › one column contains values or intervals › one column contains frequencies relative frequency histograms › similar to a histogram from count data › vertical axis represents the relative frequency of occurrence cumulative frequency plots › line graphs › classes are on the horizontal axis › cumulative frequencies are on the vertical axis

Question 13

frequency graph

Answer 13

a visual representation of data that shows how often each value (or category) appears in a dataset

Question 14

stem and leaf plot

Answer 14

a visual representation of data where each data point is divided into a "stem" (leading digit) and a leaf (last digit) › plot displays the data in a way that allows you to see spread of data, where most values clusters, and extreme outliers

Question 14

spread

Answer 14

how much variation or dispersion exists within a data set; describes how scattered the data points are within a dataset

Question 15

distribution

Answer 15

is the way data is spread or organized; describes how frequently each value occurs and provides insights into patterns and characteristics of the dataset › is symmetric when it can be cut in half by a vertical line and the halves are exact mirror images of each other › may be described as approx. symmetric if halves are close but not exact › can also be called nonsymmetric › is uniform when all values have roughly the same number of observations › can have several modes; unimodal, bimodal, and multimodal - unimodal distribution only has one peak in its distribution, bimodal has two peaks in its distribution, multimodal has three or more peaks in its distribution › if moundshaped, with a long tail of observations that trail out in one direction or other, its skewed (if it sticks out to the left, left skewed, if it sticks out to the right, right skewed › can have gaps, clusters, and outliers - gaps happen where there is a significant number of values with no observations - clusters are groups of observations at similar values - outliers are isolated observations that lie far from the bulk of the distribution - separated from it by a wide gap

Question 16

measures of center

Answer 16

mean, median, mode › mean, the sum of all values in a data set divided by the total number of values (the average) › median, the middle value in a data set when arranged in ascending order › mode, the value that appears the most frequently in a data set › important: when a data is skewed, the median is often considered a better indicator of the center than the mean, as outliers can significantly impact the mean - analyzing the relation between the mean and median can reveal information about the distribution of data (symmetrical vs. skewed)

Question 17

measures of variation

Answer 17

standard deviation & interquartile range › SD: used to test the variation in statistics by calculating the average distance from the mean of all the values in a data set- average amount of variation or dispersion in a set of data › IQR: describes the middle 50% of values when ordered from lowest to greatest; difference between the third quartile (Q3) and the first quartile (Q1) - formula : IQR= Q3-Q1 - larger IQR indicates wider spread in the middle portion of the data, smaller IQR indicates a tighter distribution - used In box plots

Question 18

average

Answer 18

the mean of the data set

Question 18

degrees of freedom

Answer 18

represent how many values in a statistical analysis have the freedom to vary without breaking any constraints › calculated as sample size - 1

Question 19

population mean

Answer 19

average value of a variable for the entire population › symbol, µ (mu) › note. while the population mean is the average for the whole population, the sample mean is the average calculated from a smaller sample taken from that population

Question 19

population

Answer 19

the entire group of individuals that a researcher wants to study and draw conclusions about

Question 20

population standard deviation

Answer 20

measure of how spread out the data points are from the mean within an entire population › average distance of data points from the population mean › symbol, σ

Question 20

population size

Answer 20

the total number of individuals within a specific group that a researcher is interested in studying › is considered a parameter, and describes a characteristic of the entire population not just a sample › note. while population size refers to the total number of individuals in the entire group, sample size refers to the number of individuals selected from that population to collect data