stats unit 1

Statistics

The science of collecting, organizing, summarizing, and analyzing data

population

entire group of individuals

sample

the subject of the population

Descriptive stats

Organizing and summarizing data through tables, groups

inferential stats

uses methods that take results from a sample- the extends to population

parameter

numeric summary of a population ex. out of all the students at mercer 75% have jobs

Variables

characteristics of individuals in populations

Qualitative

Variables allow for the classification of individuals based on characterisitics or attributes, often non-numeric in nature, such as gender or color.

Quantitative

Variables provide numerical measures of individuals can be added or subtracted

Continuous variable

a quantitative variable that has an infinite number of possibilities

discrete variable

a quantitative variable that has a finite number of possibilities

nominal level of measurements

if the values of the variable name, label, or categorize

ordinal level of measurment

if it has properties of the nonimal level of measurement and the naming scheme allows the values to be ranked

ratio level of measurement

if it has all the properties of the interval level of measurement and also has a true zero point, allowing for meaningful comparisons of ratios.

observational study

measures the value of the response variable without attempting to influence the value of either the response or explanatory variables

designed experiment

when a researcher assigns the individuals in the study to a certain group and intentionally changes the value of the explanatory variable

confounding

outside effects that could effect the results of the study

lurking variable

variable not considered but can effect the study

cross-sectional study

A study that observes a population at one point in time, collecting data from different subjects to analyze relationships between variables.

case-control study

A retrospective study compares individuals with a specific condition (cases) to those without it (controls), aiming to identify factors that may contribute to the condition.

Cohort study

A longitudinal study that follows a group of individuals over time to observe outcomes and associations with certain exposures or characteristics.

random sampling

A technique used in research to select a subset of individuals from a larger population, ensuring that each member has an equal chance of being chosen, which helps to eliminate bias.

systematic sampling

selecting very kth from the population

cluster sampling

selecting all individuals within a randomly selected collection or group of individuals

convenience sampling

when a sampling is easy to obtain and typically isn’t the most accurate representation of the population

multistage sampling

using multiple sampling techniques

sampling bias

the systematic error that occurs when some members of a population are less likely to be included in the sample than others, leading to an unrepresentative sample.

random block design

When the experiment units are divided into homogenous groups called blocks