Lab Practice 4
Write-Up
1. a. (at end)
b. The mean and standard deviation of the 8 Virgin Females group are 38.7 and 12.1.
2. a.
Days
Supp. w/8P Females
N (63.4,14 .5)
Supp. w/8V Females
N (38.7,12.1)
< 30
.2361
30 - 50
.1671
.5888
50 - 70
.4978
.1703
> 7

Lab 3 Practice
1. How many observations are there?
#Importing data
ADNI <- read.delim("~/Documents/Emory/Spring 2015/QTM Lab/Lab data sets/ADNI.txt")
There were 276 observations (and 7 variables).
2. What types of variables are present in this data set?
#

Lab 4 Practice
1. Compare the distribution of lifespan among the five experimental groups of fruitflies.
(a) Produce an appropriate figure to compare the distribution of lifespan among the five experimental
groups of fruitflies. What figure did you produc

Lab 4 Practice: Distributions
Overview
In this lab we work with distributions of random variables. The normal distribution is an example of a
continuous random variable, and the binomial distribution is an example of a discrete random variable.
Well explo

Test 1/QTM 100
Name_
Circle: 9A 2A
10/3/14
Show sketches, formulas, and work for credit.
1.
Temperature records for a certain region were kept for 20,000 days. The temperatures had an approximate normal
distribution with a mean of 65 degrees and a standar

1. Import the ADNI.txt data set. How many observations are there?
str(ADNI)
'data.frame': 276 obs. of 7 variables:
2. For each variable in the data set, describe what the variable represents in reality
(categorical or quantitative), as well as its variabl

Lab Practice 8
1. a.) The population distribution is normally distributed. The true
population mean is 1.687 and the true population standard
deviation is 0.103.
b.) Yes, the assumptions are satisfied. We know it is random
because the inference.means func

Lab Practice 2
1. What are the variable (column) names in this data set?
The variable names in the data set are year, boys, and girls
2. What are the dimensions of the data frame? (How many observations and
variables are there?)
There are 63 observations

1. Compare the distribution of lifespan among the five experimental groups of fruitflies.
(a) Produce an appropriate figure to compare the distribution of lifespan among the five
experimental groups of fruitflies. What figure did you produce?
boxplot(frui

Lab 8 Practice
1. Explore inferential results when we repeatedly sample from height m.
a. Examine the population distribution of height m
Describe the shape of the population distribution.
#Creating a histogram to see shape
hist(yrbss2013$height_m)
It is

Lab 2 Practice
1. What are the variable (column) names in this data set?
#The variables in the present data set.
names(present)
The variables are: year, boys and girls.
2. What are the dimensions of the data frame? (How many observations and
variables are

Lab 3 Practice: Summarizing and Visualizing Data
Background
Alzheimers Disease (AD) is a serious mental illness that affects an estimated 5.3 million Americans; it is
the most common cause of dementia among the elderly. Characterized by a progressive cogn

Lab 5 Practice
1. Examine the population distribution of days drink.
a. Describe the shape of the population distribution
str(yrbss2013$days_drink)
summary(yrbss2013$days_drink)
hist(yrbss2013$days_drink)
The shape is right skewed.
b. What is the true pop

Alana Ferreira
QTM LAB # 3
Jan 30th
Friday 1pm
1. Import the ADNI.txt data set. How many observations are there?
CODE: ADNI <- read.delim("~/Downloads/Lab data sets-3/ADNI.txt")
Answer: 276 observations
2. For each variable in the data set, describe what

Lab 9 Practice
1. Exploretheleadbloodlevelsofthechildrenin1972(Ld72)and1973(Ld73).
a. Arethesemeasurementspaired,ordotherepresenttwoindependentgroups.Why?
#Exploring relationship between Ld72 and Ld73
favstats(lead$Ld72~lead$Ld73)
hist(lead$Ld72~lead$Ld73

Lab 11 Practice
1. We will focus on the response variable GPA.
a. Produce a plot displaying the distribution of GPA. Which plot did you produce, and how would you
describe the distribution?
#Plotting histogram for GPA
hist(SurveySp13$GPA)
Data is left ske

Lab 6 Practice
1. Import abductees.csv and examine a summary of the data set closely. Identify any unusual features of
the data.
a. Create a new variable that corrects the coding of sex, and check your re-coding of this variable.
#Create a new cleaned ver

Edward J. Choi
1742408
QTM 100
Lab 7
1. 94 variables, mean= 4.590383, std=1.601527, plot shows spread-out variables.
2. Hypothesis Test
a) Parameter of Interest: True population mean of beauty ratings of the professors
b) H0: mu = 5
HA: mu 5
c) Yes, large

Lab 2 Practice
Namsoo Kim
2015-01-29
QTM 100
Q1. What are the variable(column) names in this data set?
A1. There are three names in this data set, Year, Boys, and Girls.
Q2. What are the dimensions of the data frame? (How many observations and variable ar

#This function performs a one-sample t-test on repeated samples from a single
quantitative variable
#variable - variable of interest
#sample.size - sample size
#alpha - level of significance
#num.reps - number of samples to draw
inference.means<-function(

Edward J. Choi
1742408
QTM 100
Lab 4
1. Unusual features of data: Some data of particular individuals are missing (NA). Also, there are
potential outliers in category of number of times abducted (abdtimes).
a) abductees$Sex
b) abductees$abdtimes2[abductee

Edward J Choi
1742408
QTM
Lab 9
1. Ld72 & Ld73
a) Paired, because both Ld72 and Ld73 represent blood levels of same 124 children.
b) observations=121; mean=3.3719 ; standard deviation=9.8532 ; normal distribution (bell-shaped)
c) 87 of 121 differences are

QTM 100
Lab 10
1. According to pharynx data, 88 of 195 (45.12%) survived at least 500 days.
2. Test (Survival of 500 days)
a) one sample z test
b) True proportion of people who survived at least 500 days post diagnosis.
c) Ho: PSurvival= 0.50; HA: PSurviv

Edward J Choi
1742408
QTM 100
Lab 6
1a) CategoricalData(n=100,p=0.41,reps=200,delay=0.05)
1b) mean = 0.411
1c) std = 0.054
1d) Normally distributed because this is binomial distribution where np >10, and n(1-p)>10.
1e)
1f) No, it wouldnt be unusual, becau

#This function repeatedly samples from a single quantitative or categorical
variable
#variable - variable of interest
#
- the variable can be either categorical yes/no or quantitative
#sample.size - sample size
#num.reps - number of samples to draw
many.s

#*
#QTM 100 Lab 1: Introduction to R and RStudio
#*
#-
#R can be used as a calculator
#-
2+2
#-
#R can be used to generate numbers
#-
1:20
#-
#R can be used to create and work with objects
#-
x<-c(2,3,5,7)
x*x
#-
#R can be used to create plots
#-

Lab 5 Practice: Sampling Distributions
Overview
In this lab we explore sampling distributions by obtaining random samples from a population. In this lab,
we consider the data set provided to be the entire population of interest so that we may explore what

1. Examine the population distribution of days drink.
(a) Describe the shape of the population distribution.
The distribution is right skewed and the center(mean=1.454) is between 1 & 2. It is
unimodal and has at least one outlier.
(b) What is the true po

1. Compare the distribution of lifespan among the five experimental groups of fruitflies.
(a) Produce an appropriate figure to compare the distribution of lifespan among the five e
xperimental groups of fruitflies. What figure did you produce?
(b) Identif

QTM Exam #2 Study Guide
CONFIDENCE INTERVALS:
Confidence Intervals (CI): an interval (AKA a range) with the most plausible values for
the parameter
Confidence level: the probability that this interval captures the parameter.
General form of CI: point esti

Exam #3 Study Guide
Inference for Categorical Data (Cont.)
Chi-Squared Test of Independence/Association
o Assesses the relationship between two categorical variables
Can have more than two categories/ levels
o Hypotheses
HO: The two variables are indepe

QTM 100 Lab 5 Practice
Namsoo Kim
2015-02-20
1. Examine the population distribution of days drink.
(a) Describe the shape of the population distribution.
The shape of the population distribution is extremely right skewed.
(b) What is the true population m