Stats Final exam
An inferential technique that uses the data from a sample to draw inferences about a population
A hypothesis test is______
u=50 and o=10
A population of scores has u=50 and o=10 if 5 points are added to every score is the population then the new mean and standard deviation would be____
the type of diet given to the rats
A recent study reports that infant rats fed a special protein-enriched diet reached an adult weight 10% greater than litter-mates raised on a regular diet. For this study, what is the independent variable?
below the mean by a distance equal to 2 standard deviations
A z-score of z=-2.00 indicates a position in a distribution
analysis of variance
ANOVA stand for
27
An analysis of variances produces dfbetween =3 and dfwithing =24 for this analysis what is dftotal?
effect size
Cohens D measures what
Nominal scale
Consists of a set of categories that have different names, measures cents on this scale label and categorize observations
interval scale
Consists of ordered categories that are all intervals of exactly the same size
discreet is number of people in this room and needs to be whole number. Continuous can go on forever
Continuous vs discreet:
tells you the average how far away you would expect the standard mean to be form population mean
Define standard error of M
deviation ; X-u
Distance from the mean and the equation
Comparing pain tolerance before and after taking a new pain medication
For which of the following situations would a repeated measures research design be approprite?
0 and 1
If an entire population with u=60 and o=8 is transformed into z-scores, then the distribution of z-scores will have a mean of ____ and a standard deviation of ____
stay constant
If other factors are held constant, the expected value of the sample mean will ___ as the sample size increases
1.00
If the null hypothesis is true and there is no treatment effect, what value is expected on average for the F-ratio
ordinal scale
Set of categories that are organized in an ordered sequence.
EX
Sum of the scores abrieviation
related samples t
Test that looks at groups before and after
r near 0
The scatterplot for a set of X and Y values shows the data points clustered in a nearly perfect circle. For these data, what is the most likely value for the Pearson correlation?
Om
The symbol that corresponds to the standard error of M is____
independent variable
The variable that gets manipulated
dependent variable
The variable that is getting measured
the alpha level
The z -score boundaries for the critical region are determined by what
the effect of one independent variable depends on the levels f the second variable
Two variables are said to interact when
that a treatment has no effect when it really does
Type II error is
When you reject the null hypothesis with more than 2 treatment condition
Under what circumstances are post tests necessary?
if we want to know whether there is an association between variables
We use the correlation method if
around 70% of the scores will be located within one standard deviation of the means
Which of the following is true for most distributions?
participants are assigned to one of two treatment groups so that each participants in one group has the same as a participant in the other group.
Which of the following studies uses a matched-subjects design?
You have a made a type 1 error
You complete a hypothesis test using alpha=.05 and based on the evidence from the sample, you made a decision is to reject null hypothesis. If the treatment actually has no effect, which of the following is true.
anytime H0 is rejected
a researcher risks a type I error when
6
a sample has SS=20 and s^2 =4. How many scores are in the sample?
the majority of the students had scores above the median
a teacher gave a reading test to a class of 5th graders and computed the mean, median and mode for the test scores. Which of the following statements cannot be accurate description of the scores?
difference and difference in populations
alternative hypothesis states
NO, but you can have 0
can you have a negative value for SS?
outcomes that are very unlikely to occur if the null hypothesis is tru
critical region
standard deviation
is the square root of the variance and provides a measure of the standard, or average distance from the mean
z-test
knows the population standard deviation and wants to compare her subjects IQ scores to a known population mean
type II error
researcher fails to reject null hypothesis and false concludes no treatment effect
psychology
scientific study of thoughts, behavior and cognition
single sample t
she wants to compare the mean of her subjects self esteem scores to a knows population mean. but she doesn't know the population standard deviation. which test
the standard error of M
the standard deviation of the distribution of sample means if called
ratio scale
this is an interval scale with additional feature of an absolute zero point.
rejecting a true H0
type I error is
It decreases
what happens to the standard error of M as sample size increases
probability
what is likelihood; fraction or proportion of all possible outcomes
no difference and no difference between populations
the null hypothesis states
three separate f ratios
the ANOVA for a two factor experiment produces what
fail to reject H0
the critical boundaries for a hypothesis test are z=+1.96 and -1.96 if the z score for the sample data is z=-1.90 then what is the correct statistical decision?
the expected value of M
the mean of the distribution of sample means is called
the mean
the measure of inferential statistics is
researcher made a mistake because chi square can be negative
) a researcher obtains a value of -8.50 for a chi square statistic
symmetrical distribution
distribution that you can draw a vertical line through the middle so that one side of the distribution is a mirror image
no one had a score exactly equal to the mode
A teacher gave a reading test to a class of 5th grade students and computed the mean, median and mode for the test scores. Which of the following statements cannot be accurate description of the scores?
two independent variables
A two factor experiment means that the experimental design includes what
concluded that a treatment has an effect when it really has no effect
A type 1 error means that a researcher has
An independent or quasi-indepenedent variable
In analysis of variance, the term factor refers to
Possibly skewed with all values greater than or equal to zero
In general the distribution of F-ratio is
large mean differences and small variances
In general, what factors are most likely to reject the null hypothesis for an ANOVA?
less than
A sample of n=10 scores is selected from a population. The variability of the score sample will tend to be ___ the variability of the scores in the population
Uses difference participants for each of the groups being compared
An independent-measures study (between measures design) does what?
9
As sample of n=8 scores has a EX =72. What is the sample mean?
decreases
As sample size increases, the standard error of M
gets smaller
As the sample size gets larger, the size of the correlation necessary for significance
The likelihood of rejecting the null increases and measures of effect size are relatively unchanged
As the sample size increases, what happens to the likelihood of rejecting the null hypothesis and what happens to measures of effect size such as r^2 and Choens D
Msbtwn/mswithin
F ratio in 1 way ANOVA equation
One-way ANOVA
If there are more than two groups and only one variable then what test
independent samples or t tests
If you are looking at different subjects within a group then what test
The mean
If you randomly choose a score from a normal distribution, what score are you most likely to select?
2 variables are measured and there is only 1 group of participants?
In a typical correlational study
independent, dependent
In an experiment, the researcher manipulates the _____ variable and measures and changes in the _____ variable
Variance
In analysis of variance, MS provides a measure of
two variances
In analysis of variance, the F-ratio is a ratio of
n: is the number of scores in each treatment and N: is the number of scores in the entire study
In the notation for ANOVA, what is referred to by the letters n and N
the actual difference between means
Inferential test statistics tend to take the sam general form. In general, what does the numerator represent?
1) state hypothesis 2) set criteria 3) collect and analyze 4) make decision 5) describe what happend
List steps to hypothesis testing
factorial design
More than one independent variable (or quasi- independent variable) - Two or more levels (conditions) for each independent variable
the grade point average for each student
One group of new freshman is given a study-skills training course during the first week of college and a second group does not receive the course. at the end of the semester, the grade point average is recorded for each student. For this study what is the dependent variable?
regression
PREDICTION within tests we use what
greater than or equal to 0; less than or equal to 1; positive numbers
Probability values are always
correlation
Relationship within test we use what test
outcomes that have a very low probability if the null hypothesis is true
The critical region for a hypothesis test consists of
the sample means for all the possible samples (for the specific sample size)
The distribution of sample means for a specific sample size consists of
There are no differences between any of the population mean
The null hypothesis for an ANOVA states that
States that there is no effect or no difference
The null hypothesis states
can never be greater than 1.00 and can never be less than -1.00
The numerical value for a correlation ______
method
The part of a journal article that offers information about the participants, materials and procedures is the ____ sections
Positive correlation
The results form a research study indicate that adolescents who watch more violent content on tv also tend to engage in more violet behavior than their peers. The correlation between amount of tv violent content and the amount of violent behavior is an example of
Normal distribution
Three general factors (sources of variance) can make group mean different from one another. Which of this following is not one of these factors?
describes exact location of a score within a distributions and tells direction and distance from the mean
What do z-scores tell us about an individual score?
the average distance between a score and a mean
What does standard deviation measure?
.7881
What is the probability of randomly selecting a z-score greater than z=-0.80 from a distribution?
symmetrical
What is the shape of the distribution for the following set of data scores? 5555, 66, 7777
only a bar graph
What kind of frequency distribution graph is appropriate for scores measured on a nominal scale?
positively skewed you use mean and if its normal skewed its mean.
When you use median or mean
a=.-10
Which alpha level provides the greatest risk of committing a type 1 error?
the t statistic uses the sample variance to estimate the population variance
Which of the following is fundamental difference between the t statistic and z score
The population correlation is zero
for a two tailed hypothesis test evaluating a Pearson correlation, what is stated by the null hypothesis?
organization and presentation of data
goal of descriptive statistics
add all the scores in the group
how to find EX
Reject null hypothesis
if a hypothesis test produces a z score in the critical region, what decision should be made?
SIGNIFICANT and we reject the null hypothesis
if large enough to be in critical region, difference is ____ and we
fail to reject the null hypothesis
if mean difference is relatively small, test statistic will have a low value and no treatment effect so we would
lines move toward each other or cross
if the results of a two factor experiment are presented in a line graph then an interaction can be seen when
the lines move towards each other or cross
if the results of a two factor experiment are presented in a line graph then an interaction can be seen whenever
Two factor ANOVA
if there are more than two groups and 2 independent variables then what test
related samples or t test
if you are looking at the same two groups then what test
-5
in a population with u=50 what is the deviation score for X=45
2 variables are measured and there is only 1 group of participants
in a typical correlational study
the average distance between means that would be expected if Ho was true and the difference between means expected by chance
inferential test statistics tend to take the same general form. In general, what does the denominator represent?
variability
provides a quantitate measure of the differences between scores in a distribution and describes the degree to which the scores are spread out or clustered together
central tendency
statistical measure that attempts to determine the single clue, usually located in the center of a distribution that is most typical or most representative of entire set of scores
level
what is the different conditions in the factorial design
-.90
which of the following Pearson correlations shows the greatest strength of consist ion of relations
