Midterm Flashcards
A number that characterizes the population is a
Parameter
What is the larger group of cases in which a researcher is interested?
Population
When should you worry about confounding variables?
In any experimental design
A number that characterizes a sample is a
Statistic
What is the biggest advantage of a correlational design?
It allows researchers to study relationships between variables as they exist in real life
Numbers _____ in how much information they contain
Numbers vary in how much information they contain
Which of these do statistics do?
They bring order to chaos
___ reveal whether cases posses more or less of some characteristic
Ordinal-level numbers
The statement “The average american household has $6969 in credit card debt” is an example of
A descriptive statistic
The variable that’s manipulated by the researcher is the what?
Independent variable
One can draw cause and effect conclusions with an experimental design when groups differ on the dependant variable and
The only difference between the groups is the independent variable
An inferential statistic
Uses a sample of cases to draw a conclusion about the larger population
Sample is to statistic as population is to ___
parameter
The subjects of a study are called what
cases
A grouped frequency table can only be used if
the intervals are of equal width
Ungrouped frequency tables work well when the
variable can have only a limited set of values
A frequency distribution is a
count of how often the values of a variable occur in a set of data
Which of these could be best represented using a grouped frequency distribution?
Salaries for first jobs of all graduating college students
Percentages are useful because
They can transform scores by putting them into context
Theoretically, _____ can be made more exact by using more precise measuring instruments
continuous numbers
_____ answer the question “how many?”
Discrete numbers
Nominal and ordinal level data are ____ and should be graphed with a ______
Nominal and ordinal level data are discrete and should be graphed with a bar graph
When creating a bar graph, the ____ goes on the Y axis
frequency
Knowing the shape of a distribution is important because:
the shape will determine whether certain statistics can be used
A distribution is considered skewed if it
is not symmetrical
What describes whether the data set us peaked or flat?
Kurtosis
Why is it important to report both a measure of central tendency and variability to describe a set of scores?
Sets of data with the same central tendency may have different patterns of variability
A measure of central tendency is used to describe the
typical or average score in a set of scores
One advantage of the median over the mean is that the median
is not as affected by the presence of outliers in a data set
If the mean is quite a bit smaller than the median, the distribution is likely
negatively skewed
The sum of a set of deviation scores will
always be equal to 0
Nominal level data; use mean, median, or mode?
Mode
A hypothesis is a
proposed explanation for observed facts
The value that the test statistic must meet or exceed in order to reject the null hypothesis is the
critical value
What does p < .05 mean?
The same results will be seen in less than 5% of the time if the null hypothesis is true
A same mean would be statistically significant if
it fell in the rare zone
Give an example of a question that would require a single-sample z test
Does a sample of purebred dogs live longer than dogs in general?
Which of these outcomes indicates that a researcher made a type II error?
Dr ross failed to reject the null hypothesis when an experimental treatment worked
If a researcher should say something happened but doesn’t, then the researcher had committed a
Type 2 error
Which of these outcomes indicates the researcher made a type I error?
Dr ross rejected the null hypothesis when an experimental treatment didn’t work
If one failed to reject the null hypothesis, one needs to consider the possibility that
A type II error was made
If consent rates are below 70%, there may be a concern that there is ____ in the study
a self-selection bias
Having a representative sample is important because it makes the
results from that study more generalizable
A ____ is a range based on a sample value, within which it’s estimated that a population value falls
confidence interval
The CLT only works when
the sample is over 30
When the SE of the mean is small, the ____ more accurately reflects the ____
sample mean; population mean
A ____ sample size is more likely to have a smaller standard error
larger
If sam opens 500 diff bags of candies and then creates a histogram of the percent of green candies in each bag, what had sam created?
a sampling distribution
The CLT describes the ____ of the means calculated when the samples are large and every possible sample is attained
shape of the sampling distribution
In a distribution of z scores, the SD will
always b 1.00
The mean of a distribution of z scores will
always be 0.00
