STAT 201 - QUIZ 1/HW1
Which of the following generally defines an inferential statistic?
A generalization about a larger group based on representative observations
simple random
Drawing a card from a shuffled deck
In order to provide improved programming, administrators of a local school district need to know how many children reside in the district, their ages, and so on. If they were to conduct a household census, they would need to measure ________ % of the households in the district.
100% A census is a complete enumeration of a population, as opposed to a sample, which measures a portion of the population. In order to conduct a census of households in the school district, they would need to measure all of its households, or 100%.
You measured the heights and weights of a random sample of 100 NHL hockey players and found that the average weight was 190 pounds. However, suppose that the actual average for all 680 players in the NHL at that time was 192 pounds. In this case, the difference between your statistic and parameter would be:
2 pounds Statistics (measured using a sample from a population) have corresponding parameters (true population values, which usually are unknown). The difference between those two values is our sampling error. Your parameter or the true population value in this case is 192 pounds, which is 2 pounds different from your sample estimate (i.e., statistic) of 190 pounds. (See "Parameters and Statistics" for more information).
The variable that is manipulated or observed in order to determine its effects on another variable is the ________ variable.
Independent the independent variable has different levels that are presented or observed.
Which of the following items is not a variable?
Maximum number of points possible on a 100-point exam
Match each of the following variables with their respective level of measurement
Nominal --> martial status Ordinal --> rating of professor from 1 to 5 interval --> IQ score Ratio --> annual salary in $USD
Which of the following types of variables are always discrete variables?
Nominal and ordinal level data can be represented as countable values.
In the Coke/Pepsi Challenge, tasters try to identify regular and diet versions of these two popular beverages under "blind" conditions, where they can't see the two products. How many levels are there to the independent variable?
4 There are two x two levels, so 4 in total.
A psychology professor assigns students in her Introductory Psychology class to participate in an experiment measuring reaction time to a variety of stimuli. This is an example of _________.
Convenience sampling Using participants that are close at hand and readily accessible might be convenient but may limit generalizability of the results.
Your professor is asking students in your class to answer a questionnaire on exam anxiety. As an incentive to participate, everyone who answers the questionnaire will be entered into a random draw for a $50 gift certificate to the campus bookstore. This draw constitutes a simple random sample in which every individual has a(n) __________ chance of winning the prize.
equal A simple random sample is one in which every element (or member of the population) has an equal chance of being selected for the sample. It is akin to drawing names from a hat. The same principle applies to a random prize draw, in which everyone has the same chance of being drawn for the prize.
Professor Stewart is interested in the extent to which job satisfaction among office workers is affected by factors in their organizational environment, such as the quality of food in a company's cafeteria. His dependent variable in this study is __________.
job satisfaction
Rank the dependent variables from a study of how job interviews are conducted in terms of complexity, from least to most complex (nominal, ordinal, interval, ratio).
job title candidate rank candidate IQ score desired salary
Which of the following variables is discrete?
martial status, the amount of money in a wallet, the number of children in a family
Sort the following levels of measurement from lowest to highest in terms of mathematical sophistication.
nominal ordinal interval ratio
A professor conducts a survey to determine whether Americans' favorite types of spectator sports varied according to their social class. The sports included hockey, soccer, football, tennis, and polo. In this survey, favorite spectator sport is at the __________ level of measurement.
nominal because of the fact that the values themselves cannot be ordered in any meaningful way. Polo is not "more than" tennis, for example. They are merely categories, without an inherent rank.
A person's grade point average on a scale from 0 to 4.0 would be a(n) ___________ ___________ variable.
ratio (absolute zero)
If an experiment is repeated, such as with different people or in different places, to confirm that the same results can be obtained, it is called _______.
replication of results
An experimental psychologist believes that memory for words is superior to memory for pictures. To test this hypothesis, the psychologist uses eight subjects selected from an introductory psychology class. Each student's memory is tested after viewing both 15 words and 15 pictures. The numbers of items of each type that each participant remembers are recorded. What is the sample in the description above?
the eight students The 8 volunteers are the people in the study, which makes them the sample.
When a test measures what it is intended to measure, the test is said to be _______.
Valid A valid test could be considered to be highly accurate.
A statistic comes from a sample, whereas a ___________ comes from a population.
Parameters are true population values, which are usually unknown due to our inability to measure entire populations.
An experimental psychologist believes that memory for words is superior to memory for pictures. To test this hypothesis, the psychologist uses eight subjects selected from an introductory psychology class. Each student's memory is tested after viewing both 15 words and 15 pictures. The numbers of items of each type that each participant remembers are recorded. What is the value of n in the study described above?
8 There are 8 people who are recruited and participate in the experiment. Fifteen and thirty are incorrect as they are related to the number of items that are presented to the sample.
Which of the following generally best describes the definition of a sample?
A subset, or smaller collection, of observations from the overall group of interest
Which of the following generally defines a descriptive statistic?
A summary or numeric observation about a group of data
A community researcher wanted to explore the connection between the number of bathrooms in a house and the sale price of the house. He studied 1000 home sales in an economically diverse, medium-sized city and found that the average sale price went up by $47,000 for each full bath. What is the descriptive statistic in this study?
Average increase in sale price of $47,000 per bathroom
While our weight is typically displayed without decimal places (e.g., 165 lbs), it can be displayed with great decimal precision. Limited only by the precision we place on it, the variable of weight is ______.
Continuous observation. Continuous variables like weight can be measured, but not counted.
Controlling for ___________ variables can help enable researchers to make statements about cause and effect relationships between variables.
Confounding Controlling any potentially confounding variables supports making correct interpretations of relationships.
A variable that is systematically different from the independent variable can prevent us from knowing what is causing an outcome or effect. This variable is known as a(n) ________.
Confounding variable A confounding variable might vary with the IV and thus interfere with being able to correctly interpret the observed relationship.
The amount of food a person eats each week (as measured in ounces) would be a ________ variable.
Continuous and ratio The ounces of food consumed have an absolute zero, representing no food, so the data are ratio level.
Rather than considering a long list of body weights for all participants in a study of weight loss, the researcher might report a single number. This is known as ______.
Descriptive statistic
A variable that consists of separate indivisible categories, for which there are no values between categories, is a _____.
Discrete variable. it can take on distinct and separate values, and are countable.
The outcome variable that we expect to change with changes in the independent variable is the ________variable.
Dependent The dependent variable is said to depend on changes made in the IV.
Why do researchers typically study samples rather than populations?
Entire populations can be too costly to study or would take too long to access. it is often very difficult or impossible to measure each and every member of a population.
An active manipulation is a key aspect of the ___ type of research design.
Experimental. The direct manipulation of an independent variable defines the experimental research design.
Which of the following types of variables are always continuous variables?
None of these are always continuous variables. Nominal and ordinal data are always discrete, while interval data can be presented as either continuous or discrete.
A study in which a researcher watches children solving puzzles, and analyzes their verbal behavior is an example of what type of research design?
Observational
What are variables?
Observations of physical, attitudinal, or behavioral characteristics that can take on different values
What are the differences between an interval and a ratio variable?
On a ratio scale, the number 0 corresponds to an absence of the quality, but this is not true for an interval scale Ratio data have an absolute zero, while interval data have an arbitrary zero.
A researcher was interested in the effects of gender on attitudes about gun control. The researcher surveyed a group of individuals, 12 of whom were men and 12 of whom were women. In this example, what is the dependent variable?
Participants' attitudes about gun control The dependent variable is the variable being measured.
A depression inventory is a scale intended to measure depression levels, with higher scores indicating higher levels of depression. If the test is a valid measure of depression, which of the following would we expect to be true?
People who get higher scores on the inventory would be more depressed than people who get lower scores A valid test would provide scores correctly relating to the level of the attribute being measured.
Systematic
Phoning every 500th name in a city phone book
Stratified
Random selection of 30 new mothers from each of 4 local hospitals
Your sample of recent (past year) immigrants includes 50% more men than exist in the actual population of recent immigrants. Because it is not representative, your sample can be called _________.
biased A biased sample is not representative of the population from which it was drawn. By systematically over-representing males in this instance, your sample can be called biased. Note that a common grammatical error is to mistake the word "bias" for "biased", as in "that sample is bias".
When a test produces consistent results, it is said to be ________.
Reliable A reliable test gives the same or very similar results each time.
In order to ensure that all subgroups in a population are adequately represented in a study, a researcher would most likely use ________ sampling
STRATIFIED
Which of the following generally best definesa population
The entire group of interest about which we want to make conclusions
James has taken the GRE three times. Every time he takes it he gets a 150 on the math section. What does this imply?
That the GRE is a reliable test Since James gets the same results each time, the test can be considered to be reliable
A researcher wanted to determine whether eating hamburgers for lunch increased the aggression of second graders during their afternoon play period. After feeding a group of 20 students hamburgers for lunch she observed that, on average, the students committed 2.5 aggressive behaviors during their afternoon play period. In this example, which of the following describes the sample
The 20 students the researcher observed
convenience
Voters in a civic election walking out of a polling station
A human factors researcher records the time it takes participants to hit a button when they hear a certain tone. The dependent variable, reaction time, is which of the following? (Select all that apply)
a continuous variable, quantitative As a measure, reaction time is measured (not counted) and tells us how much time has passed.
The following statement, "100 college-aged students participated in a study examining the relationship between gender and depression," is an example of ________ in research and statistics.
a sample the 100 students are a subset taken to represent a larger population of interest.
Which of the following variables is continuous?
age in years, currency exchange rate.
