Stats Exam 1 quizzes

Katherine examined GRE math scores of students to see the variability of ability. She found the variance to be 1600. What would the standard deviation be?

400

Which of the following groups of scores has the least amount of variability? 7, 7, 8, 10, 10 1, 2, 4, 7, 9, 10 It is impossible to determine. 1, 5, 68, 100, 110

7, 7, 8, 10, 10

In order to assess the effect of pet ownership health, a researcher surveys 150 people who own pets and 150 people who do not own pets. The sample being studied is:

300 people

Which of the following is true regarding histograms?

The frequency of each interval is represented by the height of the bars.

What would be the best operational definition of living a healthy lifestyle?

Eat 5 servings of fruits and vegetables and run for 30 minutes 3 times per week.

In comparing frequency tables with grouped frequency tables for the same set of data, which of the following would be true?

If the dataset is large, the grouped frequency table would be easier to read.

To calculate the variance, the sum of squared deviations is divided by:

N

category or name ex. names of cookies

Nominal (which is also discrete)

Suppose you see a graph titled "Changes in Happiness Across the Lifespan" and notice that levels of happiness seem to decline with age. However, when you read more about the study, you learn that "happiness" was only measured at two points in time: 20 years and 80 years. You feel that the number of times the measurement was taken might not be a very good measure of happiness because this graph displays:

an interpolation lie

In a journal article, standard deviation is abbreviated as

SD

____ are an efficient way to visually display the data to identify any outliers that may skew the distribution.

Scatter plot

Tanya wants to graph the relationship between the number of hours spent studying and student class (freshman, sophomore, junior, senior). What type of graph should be used?

bar graph

A normal distribution is

bell-shaped, symmetrical, and unimodal

different people complete tasks and comparisons are made

between groups

distributions with two clear peaks

bimodal - MODE

Why is the standard deviation typically reported rather than the variance?

Because the unit in which it is measured is same as that of the mean, a measure of central tendency

if students in a college are given an exam intended for middle school math students, it would probably result in:

ceiling effect

the descriptive statistic that best represents the center of the data

central tendency

A variable that is systematically linked with the variable a researcher believes is causing the overall effect in a study is called a ______. This variable could be the real reason an effect is seen, but we will never know because we didn't measure this other variable.

confounding

full range of values ex. time

continuous variable

Rather than listing each individual score, we group the scores into equal sized intervals and show the number of times each score occurs within that interval.

grouped frequency table

If a professor would like to graph scores from a recent exam, what type of graph should she use?

histogram

What type of graph would be appropriate to display the number of televisions owned by a sample of 100 people?

histogram or frequency polygon

In a distribution that is positively skewed, most of the scores occur on the ____ of the distribution.

left side

Scatterplots visually depict the type of relation between two variables, such as a ___ relation where the data fall along a straight line and a ___ relation, where the data follow a curved or broken pattern.

linear; nonlinear

Obtaining a measure of intelligence from a group of college students would likely yield a somewhat normal distribution (that is, there are probably no outliers). What would be the best measure of central tendency to use in this example?

mean

define the symbol M

mean

A researcher was interested in assessing whether a new medication had negative side effects on reaction time. He performed an experiment on a group of rats. One group of rats received the medication and the other group of rats did not. The researcher then measured reaction time differences between the two groups on a series of tasks. In this experiment, the independent variable is:

medication

It is possible for a distribution to have more than one

mode

Professor Taylor recently administered a psychology exam and was surprised to see that the distribution of scores was positively skewed. For this example, a positively skewed distribution indicate

most students did poorly on the exam, but a few did very well.

Professor Taylor recently administered a psychology exam and was surprised to see that the distribution of scores was positively skewed. For this example, a positively skewed distribution indicates:

most students did poorly on the exam, but a few did very well.

distributions with two peaks or more

multimodal - MODE

A distribution containing a few very small values is likely to create a distribution that is

negatively skewed

If we asked 100 people how much they like pizza, we would probably find that most people like it a lot but some people like it only a little or not at all. This would most likely be a ____ distribution.

negatively skewed

Tanya wants to graph the relation between the number of hours spent studying and student class (freshman, sophomore, junior, and senior). What should be on the y-axis?

number of hours spent studying, ranging from 0 to the highest mean value.

ranking of data ex. ranking favorite cookies

ordinal (which is also discrete)

What is the term for studies designed to examine the few participants who are very different from the majority of other participants?

outlier analysis

What type of graph is not recommended using because data can be seen/ interpreted more clearly using table or bar graph?

pie chart

A private high school wants to show that students' test scores are superior to those of another school in the district. The administration creates a bar graph showing a very tall bar representing the private school's mean test score and a very low bar representing the mean score for the other school. What part of the graph would show if the private school is exaggerating the difference between school?

range of values on the y-axis

Bar graphs are highly informative, but they can also be deceiving because what seems to be a significant difference in means may actually be a small difference. What part of the graph reveals if a difference in means is exaggerated?

range of values on the y-axis

Data that have not been transformed or analyzed are referred to as:

raw scores

When constructing graphs, it is best to include the zero value on both axes whenever practical because it:

reduces the likelihood of misinterpreting the data

An assessment that produces the same results each time it is administered is said to be:

reliable

A measure can be ________ and not ________.

reliable and not valid

In the Zimbardo prison study, students were assigned to be either a prisoner or a guard so that the experimenters could examine prison life behaviors and interactions. However, the study had to end early because students assigned to the prisoner role were suffering from psychological breakdowns. What was the independent variable in this study?

role of prisoner or guard

College students at 20 campuses were polled to find out how many students owned iPhones. This small, representative group of students is called a:

sample

define the symbol N

sample size

Interval: used with numbers that are equally spaced ex. temp of cookies Ratio: similar to intervals, but has a meaningful 0 point ex. how many cookies are left

scale variable (which is continuous)

What type of graph would be appropriate if you would like to display the relation between two scale variables?

scatterplot or line graph

Which of the following techniques for misleading with graphs involves selecting people to participate in a study so that the results turn out a certain way?

sneaky sample lie

The ________ is the most common measure of variability because it uses every score in a distribution and is easy to interpret

standard deviation

___ is the square root of the average of the squared deviations from the mean

standard deviation

________ is the square root of the average of the squared deviations from the mean

standard deviation

Numbers based on samples are referred to as ___ while numbers based on populations are referred to as ___.

statistics; parameters

define the symbol E

sum

how do you determine the full range of scores

take the highest score minus the lowest score and add one ex. 84-10 + 1 = 75

how do you determine the sum of squares

take the number minus the mean

how do you find variance

take the sum of squares and square it by two then add all of the squares up and divide it by N-1

The interquartile range is a measure of the distance between:

the 25th percentile and the 75th percentile of a data set.

Matt is interested in whether there is a difference in time spent sleeping at night in a given week between elementary-school aged children and high-school aged children. In this study, the independent variable is most likely to be:

the age of the child

Psychologists studying infant memory want to determine at what age babies can remember specific events. An experimenter uses several puppets to demonstrate a series of actions while the infant watches. After a delay, the experimenter records how many of the actions the child imitates when playing. The dependent variable is

the amount of imitated actions

In computing variance and standard deviation, we are interested in how much individual scores vary from:

the mean

Outliers have the greatest effect on the:

the mean

Displaying graphical data from a non-representative sample and making unwarranted conclusions could be referred to as:

the sneaky sample lie

the symbol N represents

the total number of scores in a sample

Sophia is interested in measuring whether there is a difference between time spent sleeping for elementary-school aged children and high-school aged children in a given week. The dependent variable is most likely:

time spent sleeping

distributions with one clear peak

unimodal - MODE

When creating histograms and frequency polygons , the x-axis typically represents ______ and the y-axis typically represents _____.

values or intervals; frequencies

In which situations is the mode more typically used

when one score dominates the distribution, when it is bimodal or multimodal, and when it is nominal

same participants do things more than once then compare

within groups (repeated measure)

When calculating variance, the SUM of the deviations is always equal to:

0

Imagine you collected eye color data for 500 people. When creating a frequency distribution, would you use a grouped frequency or an individual frequency?

Individual, because the number of possible eye colors is limited.

imagine you collected eye color data for 500 people. When creating a frequency distribution, would you use a grouped frequency or an individual frequency?

Individual, because the number of possible eye colors is limited.

Frances conducted an informal survey among women living in her sorority house. One question asked, "How many drinks do you have per week?" Frances found that the results for this question were negatively skewed. What does this mean?

Most women drink a lot, but a few do not drink much (if at all).

A sports drink company sampled 20 people who drink sports drinks and found they performed significantly better on athletic tests than those who did not drink sports drinks. What is a possible confound of this study?

People who drink sports drinks are also more active than those who don't drink sports drinks.

Lionel is presenting data on how often parents give fast food to their children. He uses pictures of a french fry for fast food and an apple for healthy food in a graph of the data. Although this graph may interesting, why should Lionel think about using a different type of graph?

Pictorial graphs may mislead the audience and detract from the actual relation between variables.

When looking at a distribution of scores that is skewed, what is the best measure of central tendency to use

The median, because it is less affected by skewness

If you calculate the standard deviation of a distribution of scores and obtain a value of 0, which of the statements is true?

There is no variability in the distribution. All of the scores are the same.

Would an analysis of outliers provide useful information even though they are not representative of most participants?

Yes, because it may reveal another factor that affects the dependent variable.

Creating a _____ table involves summarizing a group of data by listing each possible value along with how frequently the value occured.

frequency

define the symbol X

data point

define the symbol N-1

degrees of freedom

College students at 20 campuses were polled to find out how many owned iPhones. The number of owners on one campus would be an example of a(n) ______ statistic.

descriptive

Which branch of statistics uses numerical observations and incorporates them into an organized and informative summary of the data?

descriptive

Continuous observations are related to scale variables as ________ observations are related to nominal and ordinal variables.

discrete

To build a sample, the U.S. Census records the number of people in a household. What type of data is this?

discrete

variables with specific values ex. whole numbers - nominal - ordinal

discrete varibale

the ___________ lie can occur when we assume that a pattern of data will continue indefinitely.

extrapolation

method looks like it represents what it says, but really it doesn't.

false faced validity lie