Stats Exam 1

In a bell-shaped curve, the distribution is ______ around the mean

Symmetric

S2 is the notation for what value?

Variance

What is the first question you need to ask yourself about a set of data, and why is it important?

What kind of data you have so that you know how to interpret it

When might a boxplot be more desirable than a histogram for a variable?

When there are outliers

In a histogram, what do the X and Y axes represent?

X = score values Y = frequency

What are some ways a graph might be deceptive?

Y does not start at 0 and they use cartoon figures

Can distributions have more than one mode? Can they have no mode at all?

Yes they can have more than one mode (bimodel)

What are some advantages of looking at a histogram instead of a frequency table?

You can see the shape of the data

In scientific research, a sample refers to

a subset of a population

To control for the impact of time of day on the treatment outcome, a researcher should do what?

administer to all participants at the same time of day

What is an advantage of the mean as a measure of central tendency?

all values are included in the calculation

In non-experimental research design, distinctions between dependent and independent variables are sometimes ______

arbitrary

Numerical values used for categorical variables are ______

arbitrary

What is a disadvantage of the mode as a measure of central tendency?

bases on single value

You are given three pieces of information about a data set: normal, M, and SD. What picture do you draw?

bell-shaped curve

One way to create a deceptive bar chart is to use ______ instead of bars

cartoon figures

Graphs such as pie charts and bar charts are used to present ______ variables

categorical

Researchers must distinguish between categorical and quantitative variables in order to do what?

choose appropriate statistical techniques

Bell-shaped distributions tend to have values of mean, median, and mode that are ______

close to each other

Experiments require ______

comparisons

Rival explanatory variables are also known as ______

confounds

A disadvantage of graphs is that they can be presented in ways that create ______

deceptive impressions

When variable X predicts variable Y, then Y is the ______

dependent variable

The three pieces of information needed to specify the distribution, communicate it, and/or draw a sketch of it are ______

distribution shape, sample mean, and sample standard deviation

Why do we divide SS by n-1 instead of n when calculating variance?

do eliminate outliers

An advantage of frequency tables over pie charts is that they provide ______

exact frequencies and percentages

A research design in which the researcher has a high degree of control over the research situation is known as the

experimental design

Random selection and random assignment are interchangeable terms

false

On a histogram, marks on the Y axis represent ______

frequencies of each score value

Knowledge of the characteristics of the sample used for a study help the reader to assess the ______

generalizability of the results

Stating that the results of a study are applicable to others not included in the study is known as

generalization

Variability in a dataset is evaluated by examining which of the following?

how far individual scores are from the mean

What does the standard deviation tell you?

how much the values in a single sample vary

When variable X predicts variable Y, then X is the ______

independent variable

In an independent groups study, or between-S study, each participant ______

is assigned to just one group

Studies with high internal validity often have _____

low external validity

Non-experimental studies typically have _____

low internal validity

The measure of central tendency most often reported in research reports is the ______

mean

When a frequency distribution is skewed, ______ is a better way to describe the typical or common response.

median or one or more modes

Do statistics prove anything?

no, they examine variability/ make arguments

Categorical variables are also known as ______ variables

nominal

The most common way to set up a deceptive bar graph is to set up the Y axis ______

not at 0

When reading bar charts, you should pay closer attention to the ______ than to the picture

numbers on the Y axis

When subjects are ranked rather than measured, what type of variable is being used?

ordinal

Sample means are not robust when ______ are present

outliers

It is good practice to examine frequency tables, descriptive statistics, and graphs during ______

preliminary data screening

Graphs such as histograms and boxplots are used to present ______ variables

quantitative

What type of data is the number of children attending an elementary school?

quantitative

A researcher wants to study the impact of a drug education program administered in one school but not in another, with the outcome measure being self-reported intention to use drugs. The researcher has no control over program or participants. What is the research design of this study?

quasi-experimental research design

What are three measures of variability?

range, variance, standard deviation

When a study sample has characteristics of the study population it is ______

said to be representative of the population

A preliminary graph called a ______ is used to examine the relationship between variables prior to doing statistical analyses

scatterplot

How do you determine range?

subtract the minimum from the maximum

Deviation from the mean is calculated by ______

subtracting M from X

When X happens before Y occurs, then X has ______

temporal precedence

If you calculate a variance of -8.6 what does this mean?

that is how far from the mean each variable is

The variance of a sample is ______ the standard deviation of a sample

the square of

Measures of central tendency identify ______

typical or common responses

The notation used for scores for a variable is _____

x

In a bell-shaped distribution, the sum of deviations from the mean is equal to _____

0

What is the mean for the following data set: 15, 13, 9, 11, 14, 9, 12, 16

12.38

In a box plot, the middle ___ of scores lie within the box

50%

Find the median in the following set of scores: 10, 8, 7, 5, 6, 11, 14, 12

9

The smallest possible value for sample variance occurs when ______

All scores have the same value

Deviations from the mean are considered ______ for most analyses

Basic Building Blocks

If the standard deviation of a data set is low/small, this means that most values are close or not close to the mean?

Close

The height of the bar in a histogram represents the ______ in each group

Frequency

Name two types of graphs for categorical data

Frequency Tables, Pie charts

It is easier to evaluate shapes of distributions by examining ______ than by looking at frequency tables

Histograms

Name two types of graphs for quantitative data

Histograms, box plots

Box plots are useful in situations where ______ are present

Outliers

What is a population? What is a sample?

Population is any complete collection of observations or potential observations. Sample is any smaller collection of actual observations drawn from population

On a histogram, marks on the X axis represent ______

Score Values

When we examine a histogram, a question we could ask is "What is the ______ of the distribution?"

Shape

One way to obtain variation in scores is to examine the ______

Standard Deviation

S is the notation for what value?

Standard Deviation

What is the difference between Experimental and Non-Experimental studies?

In experimental studies the researcher sets up the environment and carefully controls the variables s/he is interested in. Non-experimental research takes place in a real-life setting, and it is not possible for the researcher to control all possible variables

Which variable is manipulated by the experimenter? (Independent or dependent)

Independent. DV is influenced by the IV

For group frequencies, 0 cases per group ______

Is Possible

The sample mean is denoted by which of the following?

M

What is the notation for the mean of a sample?

M or Xbar

The sum of all scores divided by the number of scores is the ______

Mean

The score value with 50% of responses above and below it is the ______

Median