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Independent Sample t Test,
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Goal(s): Increased experience with the independent sample t test. Gain expertise with how to handle interpreting the "p-value (2-tailed)," depending upon whether it is a one-tail or two-tail hypothesis test. Recognize that if the result is considered "statistically significant," then the null hypothesis is rejected.
How: For each scenario presented, take into consideration whether it is a one-tail or two-tail hypothesis test. Evaluate the "p-value (2-tailed)" result, and decide whether to reject the null hypothesis. Make 30 quick decisions, with immediate feedback.
Site: P2L.io
About
About
For this activity, the terms "Null Hypothesis Distribution" and "Ho: Null Distribution" are both used to indicate a distribution of sample means as specified by the null hypothesis.
Independent Sample t Test: The Purpose
Independent Sample t Test: The Purpose
In grade school many of us conducted the classic experiment, where there is a treatment group and a control group. After applying the treatment, we then evaluated whether a difference could be found between the treatment and control groups. The control group was our comparison, and nothing special was done with it.
To reject the null hypothesis, we want the difference between the two groups to be clear. Ideally, there would be a large difference between the treatment and control group. Within each group, the less variability the better. In this way, it would be obvious to all that a true difference exists between the two groups.
t test and p value
t test and p value
Typically, the null hypothesis for a two-tailed test is that the two group means are equal. We don't expect our two sample means to equal each other exactly, because neither is a perfect representative sample.
Retain the Null Hypothesis. A t test statistic that is close to zero indicates that the difference found between the two means is fairly common. When the t test is close to zero, you will see a corresponding large p value. This indicates that there is a high probability of getting this outcome when the null hypothesis is true. Given that the result was consistent with the null hypothesis, we retain the null hypothesis.
Reject the Null Hypothesis. The clearer the difference between the two groups (e.g., a large difference in means and/or little variability within each group), the further the t test statistic is from zero. When the t test statistic is further from zero, the reported p value will be smaller. A low p value indicates that getting this outcome is unusual when the null hypothesis is true. For a two-tailed test, if the p value is equal to or less than the alpha level, then the null hypothesis is rejected.
Alpha Level & Hypothesis Testing
Alpha Level & Hypothesis Testing
For this game, you will always be given the results as if for a two-tail test. What does it mean? You, the end user, must take into consideration whether it is a one-tailed or two-tailed hypothesis test.
If a two-tailed test, then...
Reject the null hypothesis when the 'p-value (2-tailed)' ≤ .05
If a one-tailed test (e.g., "Group1 >= Group2"), then...
Retain the null hypothesis if the results are consistent with the null hypothesis
Otherwise, reject the null hypothesis:
If 'p-value (2-tailed)' ≤ (2 x alpha level).
For a one-tailed test, with the sample mean in the direction opposite of that predicted by the null hypothesis, with a p-value (2-tailed) of .09, and an alpha level of .05, we would reject the null hypothesis.Which can also be stated as: reject the null if ('p-value (2-tailed)' / 2) ≤ .05.
That is to say, for a one-tailed hypothesis, if the results are consistent with the null hypothesis, then retain it. Otherwise, compare the 'p-value. (2-tailed)' to a value that is double the alpha level (e.g., 2 * .05 = .10); for an alpha of .05, reject the null if the 'p-value (2-tailed)' ≤ .10. Alternatively, one could halve the 'p-value (2-tailed)' and compare it to the alpha level (e.g., .05). Mathematically, these two methods will give the same result, so pick whichever approach you find easier to apply.
Game
Optional: Earning Class Credit
To earn credit for this activity:
Click the 'Accommodations' button on the game menu.
Using the number pad (in the Accommodation dialog box), type the passcode provided by your instructor.
Click the 'Continue' button. Doing so will return you back to the game menu.
Then click 'Start' to begin the game.
When you complete the task with a score of 85% or greater, you will be given a completion code. To view this completion code, click on the 'Completion Code' button.
To get credit for having completed the activity, provide the completion code as your answer (e.g., to a quiz question). If the completion code is not yet available (e.g., performance was less than 85%), then click the 'Continue' button to re-do the activity.
Accommodations include:
Screen Reader (click the 'Screen Reader' button)
Unlimited decision time (e.g., Click the 'Accommodations' button, then type #17 by itself or at the end of a passcode. Click 'Continue').
Please notify your instructor if requesting these accommodations.
Instructors can modify games and set up quizzes rather easily. Check out game modifications.
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