HW
Qualitative variables
Qualitative variables allow for classification of individuals based on some attribute or characteristic. Quantitative variables provide numerical measures of individuals, and can be added or subtracted and provide meaningful results.
There is not one particular frequency distribution that is correct, but there are frequency distributions that are less desirable than others.
The statement is true. Any correctly constructed frequency distribution is valid. However, some choices for the categories or classes give more information about the shape of the distribution.
It is extremely important for a researcher to clearly define the variables in a study because this helps to determine the type of analysis that can be performed on the data. For example, if a researcher wanted to describe people based on Social Security number, what level of measurement would the variable "Social Security number" be? Now suppose the researcher felt that certain people with a greater birth weight received higher numbers. Does the level of measurement of the variable change? If so, how?
What is the level of measurement of the variable "Social Security number" in the original scenario? Nominal Does the level of measurement of the variable change in the second scenario? Select the correct choice below and, if necessary, fill in the answer box within your choice. A. Yes, it changes to ordinalordinal.
A news service conducted a survey of 1064 adults ages 18 years or older in a certain country, August 31−September 2, 2015. The respondents were asked, "Of every tax dollar that goes to the federal government, how many cents of each dollar would you say are wasted?" The four possible responses are that the federal government wastes less than 10 cents, between 11 cents and 25 cents, between 26 cents and 50 cents, or 51 cents or more. Of the 1064 individuals surveyed, 35% indicated that 51 cents or more is wasted. The news service reported that 35% of all adults in the country 18 years or older believe the federal government wastes at least 51 cents of each dollar spent, with a margin of error of 6% and a 99% level of confidence. Complete parts (a) through (e) below.
What is the research objective? to determine the percentage of adults in the country who believe the federal government wastes 51 cents or more of every dollar (b) What is the population? Adults in the world aged 18 years or older (c) What is the sample? The 1064 adults in the country that were surveyed (d) List the descriptive statistics. Choose the correct answer below. 35% of the individuals surveyed indicated that 51 cents or more is wasted. (e) What can be inferred from this survey? The news service is 99% confident that the percentage of all adults in the country who believe the federal government wastes 51 cents or more of every dollar received is between 29% and 41%
What does it mean when sampling is done without replacement?
When sampling without replacement, once an individual is selected, the individual is removed from the possible choices for that sample and cannot be chosen again. Next Question
uniform symmetric
[------]The given graph is skewed in the direction of the tail
Right skewed
[/\___]
left skewed
[___/\] The given graph is skewed in the direction of the tail
Case-control studies
are retrospective studies, meaning that they require individuals to look back in time or require the researcher to look at existing records. In case-control studies, individuals who have a certain characteristic may be matched with those who do not.
experiment
as a controlled study conducted to determine the effect varying one or more factors has on a response variable, and any combination of the values of the factors is called a treatment. Therefore, the goal of an experiment is to determine the effect that the treatment will have on the response variable
Descriptive statements
give information that is known.
Researchers studied 350 people and matched their personality type to when in the year they were born. They discovered that the number of people with a "cyclothymic" temperament, characterized by rapid, frequent swings between sad and cheerful moods, was significantly lower in those born in the summer. The study also found that those born in the spring were less likely to be irritable, while those born in winter were more likely to be depressive. Complete parts (a) through (e) below.
(a) What is the research question the study addresses? Does season of birth affect mood? (b) What is the sample? The 350 people in the study (c) What type of variable is the season in which you were born? qualitative, nominal. d) What can be said (in general) about individuals born in summer? Winter? People born in summer are less likely to have mood swings. What can be said (in general) about individuals born in winter? People born in winter are more likely to be depressive. (e) What conclusion was drawn from the study? Season of birth plays a role in one's temperament.
is one in which each experimental unit is randomly assigned to a treatment.
A completely randomized design
A continuous variable
A continuous variable is a quantitative variable that has an infinite number of possible values that are not countable.
A discrete variable
A discrete variable is a quantitative variable that has either a finite number of possible values or a countable number of possible values. The term "countable" means that the values result from counting, such as 0, 1, 2, 3, and so on.
interval
A variable is at the interval level of measurement if it has the properties of the ordinal level of measurement and the differences in the values of the variable have meaning.
nominal
A variable is at the nominal level of measurement if the values of the variable name, label, or categorize.
ordinal
A variable is at the ordinal level of measurement if it has the properties of the nominal level of measurement, but the naming scheme allows for the values of the variable to be arranged in a ranked or specific order.
ratio
A variable is at the ratio level of measurement if it has the properties of the interval level of measurement and the ratios of the values of the variable have meaning.
In statistics, results are always reported with 100% certainty.
False. In statistics, results are not reported with 100% certainty. Because statistical studies draw on samples, and because there is variation within groups, results cannot be reported with 100% certainty.
Inferential statistics
Inferential statistics uses methods that take a result from a sample, extend it to the population, and measure the reliability of the result
A matched-pairs design
is an experimental design in which the experimental units are paired up. The pairs are selected so that they are related in some way (that is, the same person before and after a treatment, twins, husband and wife, same geographical location, and so on).
A randomized block design
is used when the experimental units are divided into homogeneous groups called blocks. Within each block, the experimental units are randomly assigned to treatments
relative frequency distribution (add up to 1)
lists each category of data together with the relative frequency. The frequency column sums to the total number of observations. The relative frequency is the proportion (or percent) of observations within a category.
In a uniform distribution,.
the frequency of each value of the variable is evenly spread out across the values of the variable
In a bell-shaped distribution,
the highest frequency occurs in the middle and frequencies tail off to the left and right of the middle.
In a distribution that's skewed left,
the tail to the left of the peak is longer than the tail to the right of the peak.
In a distribution that's skewed right,
the tail to the right of the peak is longer than the tail to the left of the peak.
The lower lass limit is the smallest value within the class
the upper class limit is the largest value within the class.
Inferential statements
use known information to make predictions about unknown things that are related.
