Exam 10: Independent Groups T-Test

When the observed t value is larger than the positive critical t value or smaller than the negative critical t value,this suggests that the observed mean difference can be attributed to sampling error.

What is eta-squared?

A treatment effect

An independent groups t-test has _____levels of the independent variable.

Dr.Johnson is studying the effects of aspirin on heart rate.He believes that aspirin will lower heart rate.He has 2 groups the treatment group receives 80mg of aspirin for a week (n=4)the control group received a placebo (n=4)and their heart rates are compared.Below is his data in which heart rate is beats per minute.He sets his alpha level at 0.05 and uses a directional test. Can you reject the null hypothesis and concluded that aspirin lowers heart rate?

Independent-groups t tests may be used to analyze the relationship between two variables when _____.

A physical therapist is interested in whether people with different bone structures will be affected differently by her new therapy program.She randomly chooses two groups of patients based on bone type: small-boned frame (X_S)and large-boned frame (X_L).Patients all had similar injuries.She measures the number of days each person takes to progress to a predetermined point.Here is the data: What is the estimated standard error of the difference?

JJ just used an Independent groups t-test to analyze his data for his Master's degree and found that the t-value or his calculated t was equal to 3.05 based on his degrees of freedom of 60.The table t was 1.671 and he set his alpha level at .05 directional.Can he reject the null hypothesis and conclude the groups are significantly different.

The null hypothesis in the independent groups t test is that a population mean has a specific value,specified by the investigator.

The stronger the influence of the independent variable on the dependent variable,the larger the sum of squares error should be relative to the sum of squares total,everything else being equal.

The amount of sampling error is determined by_____.

When sample sizes are small,power will tend to be __,everything else being equal.

The proportion of sample variability in the dependent variable that is explained by the independent variable is called eta-squared.

It is important to calculate the _________even if the results indicate there is not a significant difference between groups.

A physical therapist is interested in whether people with different bone structures will be affected differently by her new therapy program.She randomly chooses two groups of patients based on bone type: small-boned frame (X_S)and large-boned frame (X_L).Patients all had similar injuries.She measures the number of days each person takes to progress to a predetermined point.Here is the data: What is the pooled variance estimate?

If there is equal variance in groups or homogeneity of variance then the variance would be ó₁² = ó₂² = ó^2.

The size of the standard error of the difference is influenced by:

The alternative hypothesis for an independent-groups t test states that _____.

The total variability in the dependent variable,as represented by SS_TOTAL,can be split up,or partitioned,into two components,one (SS_EXPLAINED)reflecting the influence of the independent variable and one (SS_ERROR)reflecting the influence of disturbance variables.

Eta-squared is a biased estimator in that it tends to slightly underestimate the strength of the relationship in the population across random samples.