STATS 251 Exam 1

descriptive statistics

organizing, summarizing, and visualizing data

inferential statistics

drawing conclusions from data

from the data. what can you say about a whole group from a study

population

a collection of persons, things, or objects of interest for studying and understanding

sample

a selected subset of the population that will be used for population inference

what do we need to consider when finding a sample

it should be representative of the whole population

population parameter

a fixed number that describes an entire population

ex) average income, average lifespan, average test score

sample statistic

a specific number that describes a sample from the population

what can we do with a simple sample statistic

used to estimate unknown characteristics of a larger, broader population

simple random sampling

each sample of the decided size has the same chance of being selected

systematic sampling

every certain number will be in the sample

ex) every 10th, 20th unit will be in the sample

cluster sampling

divide the population into smaller parts that are similar to one another. then, choose a group from each of the clusters

convenience sampling

non-probability research method

researchers choose their participants based on how easy they are to reach or how willing they are to join

stratified sampling

dividing population into groups and selecting individuals from each group

qualitative

data that describes qualities, categories, or characteristics. This data can’t be measured with numners

quantitaive discrete

data that is measurable with countable whole numbers

quantitative continuous

data that is measurable with decimals

another word for qualitative variables

categorical

ordinal vs nominal

another word for quantitative variables

numerical

continuous or discrete

ordinal data

data with rank or sequence

frequency tables

population is split into groups, and the frequency table reports count of each group

relative frequency table

gives percentage for each freqency

bar chart

visual tool that uses rectangular bars to compare data

pareto chart

graph that combines bar chart and a line graph to show which factors have the largest impact

Pie chart/ring chart

circular graph divided into proportional slices to show how the different parts relate

bivariate analysis

categorical vs categorical

histogram vs bar chart

histograms shows the distribution of continuous numerical data

bar graphs display categorical data

how to analyze bar graph

shape, center and spread, outliers, and gaps

modality

unimodal, bimodal, multimodal, uniform

symmetry

symmetric, left skewed, right skewed

median

middle data point

mean

add all numbers and divide by the number of decimals

mode

value that happens the most frequently

measures of spread