STAT 121: Writing Assignment 2
Significance Test and Confidence Interval (24 points)
Directions: Read the following problem, and follow directions, and answer each question
completely but concisely. Be sure to save a copy of your work, and see the syllabu
STAT 121: Writing Assignment 1
Confidence Intervals (13 points)
Directions: Read the following article and answer each question completely but concisely. Be
sure to save a copy of your work, and see the syllabus for submission details. (The spacing
Know how to interpret slope in a least squares regression line
Slope tells us the average "increase" (positive slope) or "decrease" (if slope is negative) in y for each one
unit increase in x. When interpreting, you need to first determine what the x and
Know why random sampling and random allocation are so important
So we can do inference.
Be able to identify the population of interest, the response variable and the sample
The population is the entire group of individuals about which the researcher wishe
Be able to compute a confidence interval for slope
Use the first value in the second row as the estimate and the second value in the second row as SEb; find
t* using t table using df = n - 2. Remember that the formula for df is given on the formula sheet.
Explanatory vs. Response variable in terms of regression
In regression, the response variable is the one we want to predict (the y) and the explanatory variable is
the x variable (i.e., the variable we use to do the predicting.)
Be able to construct and i
Be able to decide whether to use the five-number summary or mean and standard deviation to describe
a data set
Moore recommends using the five-number summary in the presence of outliers.
Know how to find a probability on an individual for a given x-value
Know the four parts of statistics
It's the study of data analysis-defining the problem, collecting data, analyzing and summarizing data, and
drawing inferences from data.
Know the definition of distribution
A list of the possible values of a variable toge
lack of realism
weakness in experiments where the setting of the experiment does not realistically duplicate the
conditions we really want to study.
law of large numbers
the true probability of an event "A" is estimated by the relative frequency with whic
sample where the researcher contacts those subjects who are readily available and does not use any
random selection. the results are almost surely biased.
sampling conducted when the population is naturally divided into
A condition that occurs when the design of a study produces a sample that is not representative of the
The grouping of individuals according to some characteristic like rats in the same litter or plots of land at
the same locatio
BM 121 MW 10am
Week 1: September 20th- 26th; 1 Nephi 7:16- This scripture talks about frankly forgiving
Living this scripture of forgiveness proved to be much harder but much more
fulfilling than I had thought it would be. In
Writing Assignment #1
1. The population that the confidence interval is making an inference about is
all adult Americans (ages 18 or older)
2. The parameter of interest is the true average heart rate of all adult
Know the advantage of an experiment over an observational study
Experiments are used to establish causation (a cause and effect relationship between the explanatory
and response variables) and observational studies cannot be used to establish causation.