Stats Mid Term

science of data

objects being described by set of data

any characteristic of an individual and can take on different values

numeric

wordy

particular things variables take on

observes individual and measures variables of interest but does not influence responses.  used to describe group or situation

variable that measures an outcome or result of a study

to gain info of whole through one part

survery goup of individuals by studying only some of members. it represents the larger group

entire group of individuals about which we want information (group want to study)

part of population from which we actually get the information and use it to draw conclusions about the whole

sample survey that attempts to include entire population in sample

deilberately imposing some treatment on individuals to observe responses.  can give cause and effect

statisitical study that systematically favors certain outcomes.

selection of individuals who are easiest to reach

chooses itself by responding to a general appeal (call in)

choose a sample of n individuals form the population by a way that every set of n individuals has a chance to actually be selected

• long string of digits with two properties...
• 1. each entry is equally likely to be 0-9
• 2. entires are independent of each other

number that describes the population

number that describes a sample

population; sample

describes how spread out values are

simple random sample

proportion (fraction thats divided)

statistic

plus or minus 2% points of how close sample stat is to pop parameter

truth lies within the margin of error ( what % of all possible samples satisfy margin of error)

• fact about what happens in all possible samples and is used to say how trustworthy result of sample is
• 1. margin of error
• 2. level of confidence

• errors caused by thw act of taking a sample
• -undercoverage
• -random sampling error
• -biased sampling methods

deviation between sample stat and the population paramenter cause by chance in selecting a random sample

• errors not related to the act of selecting a sample from the population
• -processing erros
• -response error
• -nonresponse

list of every individual from population

occurs when some groups in population are left our of process of choosing the sample

mistakes in mechanical tasks like arithmatic or entering responses into a computer

when subject gives incorrect response  (lie, guess, bad memory)

failure to obtain data from individual selected for a sample (cant contact or no coorpation)

• 1. strata - divide sampling frame into distinct groups of individuals
• 2. clusters - take separate SRS in each stratum and combine to make complete sample

sample chosen by chance

variable that measures an outcome or reult of study (dependent)

variable that we think explains or causes change to response variable (independent)

individuals studied in an experiment

specific experimental condition applied to subjects

variable that has important effect on relationship among variables in study but isnt one of explanatory variables studied

when 2 variables have effect on a response variable and cannot distinguish from each other

experiment that studies effectiveness of medical treatments on actual patients

dumby treatment with no active ingredients

response to dumby treatment

neither subjects nor testers recording know which treatment was to who

one that compares two treatments and allow us to draw cause and effect and is random and compares two things that are actually operating equally

can be placebo group (no treatment at all)

effects of lurking variable on response, most simply by comparing 2 or mor treatment 

use impersonal chance to assign subjects to treatments

observed effect of a size that would rarely occur by chance

good, compare in observance

combine comparison in creating a control group

subjects who participate but do not follow the experimental treatment

those hwo begin an experiment that continues over extended period of time then they do not complete it

accurate of whole population

experimental design, all the experiemental subjects are allocated at random among all treatments

compares 2 treatments that the pairs of subjects are closely matched as possible

random assignment of subjects to treatment is carried out sepaately within each block

experimental subjects that are similar in some way prior to experiment that is expected to affect response of treatments

a property of person or thing that we assign a number to represent the property

make a measurment

used to record the measurment

result of measurement is numberical

meassure of a property if it is relevant or appropriate as a representation of that property

can be used to predict success on tasks that are related to the property measured

sustematically tends to overstate or understate true value of measured property

repeated measurements on same individual but gives different results

if random error is small

several repeated measurements of same individual is more reliable than a single measurement

variable that tells us what values it takes and how often it takes these

• raw data 
• values || frequency

rounded entries dont quite add to total which is rounded seperately

show how a whole is divided into parts and forces us to see parts that make a whole

help distinguish tween variables whose values have meaningful numerical scale

places individual into one of several groups of categories

takes numerical values for which arithmatic operations like ading and averaging make sense

bar graph in whic pictures replace bars and ar not proportional

to display change over-time and plits each variable against time 

distribution of quantitative variable and bars touch

midpoint of distribution

variability of data (dont count outliers)

peaks (unimodal, bimodal, mutlimodal), symmetric

when the tail goes to the right

when the tail goes to the left

stem is on the left and leaves are on the right

midpoint of distribution, the # that is positioned half way tween all the observations

midpoints from beginning to median and median to end and divides observations into quarters

min, Q1, median, Q3, max

graph of five num sum

average of set of observations

most frequent number

measures average distance of observations from mean