STATS Final
What are the assumptions for a related sample t-test
1. Normality: We assume that data in the population difference scores are normally distributed. 2. Independence within groups: the samples are related between groups and we assume that difference scores were obtained from different individuals within each group.
State three advantages for using related samples in behavioural research
1. can be more practical 2. reduces standard error 3. increases power
Name the t test used in hypothesis testing to evaluate the mean observed in one sample.
A one-sample t test is used to compare a mean value measured in a sample to a known value in the population.
State the critical values for a two-independent sample t test given the following conditions: a) Two-tailed test, alfa=.05, n=12 in each group b) One-tailed test, lower tail critical, alfa=.012.602, df=15 for each group c) Two-tailed test, alfa=.01, total df=26 d) One-tailed test, upper tail critical, alfa=.05, n for both groups combined is 30
A. 2.201 B. 2.602 C. 2.779 D. 1.697
State the total degrees of freedom for the following t tests: a) n=23 for a one-sample t test b) degrees of freedom = 12, n sub 2 = 19 for a two independent sample t test c) Critical value=1.645 for a one-tailed test, alfa=.05 d) Critical value=63.657 for a two tailed test, alfa=.01
A. 22 B. 18 C. infinity D. 1
In the following studies, state whether the one-sample t test is an appropriate test statistic to analyze data. If not, then explain why it is not appropriate. a) A study measuring differences in attitudes about morality among democrats and republicans b) A study testing whether night-shift workers sleep the recommended 8 hours per day. c) A study evaluating the body mass index score of athletes compared to the general population.
A. Appropriate B. Not appropriate, z test because we are testing for a single Mu C. Appropriate
Would each of the following increase, decrease, or have no effect on the value of the test statistic for a related-sample t test? a) the sample size is increased. b)The level of significance is reduced from .05 to .01 c) the estimated standard error for difference scores is doubled d) the mean difference is decreased
A. Decrease B. No effect C. Decrease D. Reduce
Will each of the following increase, decrease or have no effect on the value of the test statistic in a one-sample t test? a) The sample size increased b)The level of significance is reduced from .05 to .01. c) The sample variance is doubled d) The difference between the sample and population mean is increased.
A. Decrease B. No effect C. Decrease D. Increase
What is the decision at a .05 level of significance for each of the following tests? a) F(3, 26) = 3.00 b) F(5,20)= 2.54 c) F(2,12)= 3.81 d) F(4,30)= 2.72
A. Failed to reject B. Failed to reject C. Failed to reject D. Failed to reject
State whether each of the following is an example of a positive correlation or a negative correlation. a) higher education level is associated with a larger annual income b) the smaller the class size, the more students believe they are receiving a quality education. c) increased testosterone is associated with increase aggression d) rising prices of apples are associated with the sale of fewer apples.
A. Positive B. Negative C. Positive D. Negative
For each example, state whether the one sample, two-independent sample, or related sample t test most appropriate. If it is a related-sample t test, indicate whether the test is a repeated-measure design or a match pairs design. a) A professor tests whether students sitting in the front row score higher on an exam than students sitting in the back row. b) A researcher matches right handed and left handed siblings to test whether right-handed siblings express greater emotional intelligence than left-handed siblings c) A graduate student selects a sample of 25 participants to test whether the average time students attend to a task is greater than 30 minutes d) A principal at a local school wants to know how much students gain from being in an honors class. He gives students in an honors English class a test prior to the school year to measure how much students learned during the year.
A. Two independent sample, because they are comparing two samples B. Related sample t test because it's a match pair design C. One sample t test D. Related sample t test because it's a repeated measure design
In the following studies, state whether you would use a one-sample t test or a two independent sample t test. a) A study measuring differences in attitudes about morality among men and women b) A study testing whether night shift workers sleep the recommended 8 hours per day c) An experiment measuring differences in brain activity among rats placed on either a continuous or an intermittent reward schedule.
A. Two-sample t test B. One-sample t test C. Two-sample t test
A medical study found a negative relationship between exercise and stress-related health problems (r=-.26). Which of the following conclusions is appropriate? Explain why the other is not appropriate. a) 6.76% of the variance is stress-related health problems can be explained by the amount of weekly exercise b) increasing the amount of exercise per week will cause stress related health problems to decrease.
B is appropriate because theirs an indirect relationship. A is not appropriate because there isn't an inverse relationship.
A social psychologist records the number of outbursts in a sample of different classrooms at a local school. What are the sample size, decision, and effect size in this study? The number of outbursts among students at this local school (M=3) was significantly less than that in the general population, t(39)=4.19, p is less than .05 (d=0.25).
Cheg
What is the difference between a one-way ANOVA and a two-way ANOVA
One-Way ANOVA tests the difference in population means based on one characteristic or factor. Two-Way ANOVAtests comparisons between populations based on multiple characteristics
What is a correlation
Describes the strength and direction of the linear relationship between two factors.
Name two measures of proportion of variance. Which measure is least conservative.
Effect size and omega squared. Omega squared being least conservative.
A researcher conducts a one-way ANOVA in which one independent variable has four levels. How many different groups are in this study?
Four
Distinguish between related samples and independent samples
Independent samples are only observed once and are not related. In related samples, the participants are observed in more than one group or they are matched experimentally based on common characteristics or traits.
What is the coefficient of determination
It's equivalent to eta-squared and is used to measure the proportion of variance of one factor (y) that can be explained by known values of a second factor (x).
Define Mean square between groups
Mean Square Between groups compare the means of groups to the grand mean
Four assumptions for the two-way between-subject ANOVA
Normality, random sampling, independence, and homogeneity of variance
Of the two ways to select samples described in this chapter, which type of sampling is commonly used in experiments?
One sample t test
Explain the meaning of the following terms for an ANOVA: a) one-way b) between-subjects, c) within-subjects
One way: tests for one factor Between-subjects: variance of the group means Within-subjects: variance attributed to error
What is an in-between subject design ?
Research design in which different participants are observed one time in each group
How does the shape of a t-distribution change as a sample size increases?
Since a t distribution is an estimate of a normal distribution, the larger the sample size, the more closely it estimates a normal distribution.
What is the main limitation of the z test? Name an alternative to the z test that does not have this limitation.
The main limitation of a z-distribution is that we need to know the population variance. The t-distribution has greater variability in the tails.
Define Sum of squares between groups
The sum of squares attributed to variability between groups
Define Sum of square error
The sum of squares attributed to variability within each group
When looking at a graph of an A * B interaction, describe the patterns that indicated that the interaction is possibly significant.
When looking at a graph significance is possible when two lines cross each other.
State the degree of freedom error in each of the following between-subject tests? a) A research tests how nervous public speakers get in front of a small, medium, or large audience. Ten participants are randomly assigned to each group. b) A consultant measures job satisfaction in sample of 15 supervisors, 15 managers, or 15 executives at a local firm. c) A high school counsellor has 12 students in each four classes rate how much they like their teacher.
a) Total df =30-1=29 Between group df =3-1=2 Error df =29-2=27 b) A consultant measures job satisfaction in sample of 15 supervisors, 15 managers, or 15 executives at a local firm. Total df =45-1=44 Between group df =3-1=2 Error df =44-2=42 c) A high school counsellor has 12 students in each four classes rate how much they like their teacher. Total df =48-1=47 Between group df =4-1=3 Error df =47-3=44
State whether each of the following related-sample t tests is significant for a two tailed test at a .05 level of significance. a) t(30) = 3.220 b) t(18)= 2.034 c) t(12)= 2.346 d) t(60)= 1.985
a) t(30) = 3.220 the critical region for 30 = t>2.042 hence the test is significant b) t(18) = 2.034 critical region for 18 = t>2.101 hence the test is significant c) t(12) = 2.346 the critical region for 12 = t> 2.179 hence the test is significant d) t(60) = 1.985 the critical region for 60 = t>2 as the value is less therefore the test is not significant
State the total number of groups for each of the following examples of a two-way between subjects ANOVA test a) A psychologist administers a small, medium, or large dose of a drug to a sample of mice and measures reward-seeking behavior in three experimental trials b) An industrial-organizational psychologist measures the GPA among men and women graduate students with low, medium, or high leadership potential
a)There are total 3 groups which consists of small, medium, or large dose of a drug. b)There are total 5 goups: 1) 2 groups of GPA among men and women graduate students and 2) theree groups of low, medium, or high leadership potential.
State which correlation coefficient (Pearson, Spearman, point-biserial, or Phi) should be used given the following information a) both factors are interval or ratio scale b) Both factors are ranked c) One factor is dichotomous, and the other factor is continuous d) Both factors are dichotomous.
a. pearson b. Spearman c. point biserial d. phi
A psychotherapist asks a sample of violent and nonviolent criminals from impoverished, middle class, and upper-class backgrounds to indicate how accountable they feel they are for their crimes. Identify each factor and the levels of each factor in this example
chegg
For each of the following, state whether F=0 for a main effect, A x B interaction, or both. a) Cell means are equal b) Row totals are equal c) Column totals are equal
chegg
What information does the strength of a correlation coefficient convey
it describes how strongly variables are related to one another. A correlation level of 0.05 is needed in order to consider a correlation as being moderately strong, an indication of statistical significance.
