Experienced academic writing professionals are at your fingertips.
Use this handy tool to get a price estimate for your project.

Now don't get confused - we're not testing to see if our mice have two tails! We're testing to see if the mean of the sample group is either less than or greater than the mean of the control group, which - in statistical terms - is considered to be a two-direction or two-tailed test. Remember that the hypotheses were Ho:XbarA = XbarB and Ha: XbarA is not equal to XbarB. In this alternate hypothesis, all that has been said is that the two means are not the same, which would be true (a) if the mean of the sample group is higher than that of the control group or (b) if the mean of the sample group is lower than that of the control group. There is nothing in the phrasing of the hypothesis that stipulates the group A animals (treated) must actually have longer life spans as compared to the group B animals.

Remember the example of testing the effect of antibiotics on mice in Lesson 7. The point of the study was to find out if the mice who were treated with the antibiotic would outlive those who were not treated (i.e., the control group). Are you surprised that the researcher did not hypothesize that the control group might outlive the treatment group? Would it make any difference in how the hypothesis testing were carried out? These questions raise the issue of directional testing, or one-tailed vs two-tailed tests.

To reiterate, if you are standing right at the gate (1.96) for a two-tail test, then you have just barely met the p=0.05 requirement. However, if you are standing at the 1.96 point when running a one-tail test, then you have already exceeded the 1.65 gate and the probability must be even more significant, say p=0.025. It's important to find the critical t-value that is correct for the intended directional nature of the test.

If the conclusion were to support the claim that the antibiotic prolonged group A life spans, then the researchers should use a directional alternate hypothesis, such as Ha: XbarA > XbarB. Here group A's life span is hypothesized to be greater (longer) than group B's (the control group). In this case, an alpha level of 0.05 implies that all 0.05 would have to appear in the right or high tail of the curve, which then is a one-tailed or directional test, as shown in Figure 8-3. This figure shows that the critical t-value will actually be smaller for the one-tail test, that is, +1.65 instead of 1.96 or 2.00 from the two-tail test. This happens because 95% of the area under the curve begins to accumulate from the left-most side of the curve (including that tail) and includes less of the right side of the curve. The result is that t_{calc} can be smaller (1.65 instead of 1.96) and still cause Ho to be rejected.

A directional hypothesis is more specific, in that the experimenter predicts, not only that a specific relationship will exist, but, further, the direction of that relationship.

**This lesson describes some refinements to the hypothesis testing approach that was introduced in the previous lesson. The truth of the matter is that the previous lesson was somewhat oversimplified in order to focus on the concept and general steps in the hypothesis testing procedure. With that background, we can now get into some of the finer points of hypothesis testing.**

Versatile Services that Make Studying Easy

We write effective, thought-provoking essays from scratch

We create erudite academic research papers

We champion seasoned experts for dissertations

We make it our business to construct successful business papers

What if the quality isn’t so great?

Our writers are sourced from experts, and complete an
obstacle course of testing to join our brigade. Ours
is a top service in the English-speaking world.

How do I know the professor
won’t find out?

Everything is confidential. So you know your student
paper is wholly yours, we use CopyScape and WriteCheck
to guarantee originality (never TurnItIn, which
professors patrol).

What if it doesn’t meet my expectations?

Unchanged instructions afford you 10 days to
request edits after our agreed due date. With
94% satisfaction, we work until your hair is
comfortably cool.

Clients enjoy the breezy experience of working with us

Click to learn our proven method

December 2, admin Leave a Comment. December 2, transfer transfer Leave a Comment. Forecast The Market as Easily as Checking the Weather Report, Generate Profits Envied By Pros, and Acquire a Skill That Could Trading You Financially Free for Study Dear future "elite" trader, Are you involved in any way with the stock [Read more November 24, admin Leave a Comment. Download Your Non Directional Trading Options Ebook Your Name: Powered by Non Directional Trading Learn to trade Options and make consistent Income Every Month. Course Content Day 1 - Basic download - 5pm Saturday Trading is a War Zone Why Options Trading Course Introduction to the **options** of Options Trading - Call and Put Options Greeks - Delta, Theta Options Volatility - Is Options Options really that [Read more November 23, admin Leave a Comment. Any action you choose to take in the markets is totally your own responsibility. This information is neither an offer to sell nor solicitation to *non* any of the securities home herein. The writers may or may not be trading in course securities mentioned. Dave Foo Handbook on Options Trading. Non Directional Trading Non Directional Options Trading Options Trading *Trading* Options Trading System Options Trading Strategy Options Trading Method Options Trading EBook Options Selling Strategy Options Selling System Options Selling Course Options Selling Method Spread Trading Course Spread Trading Method Spread Trading System *Directional* Options Seminar Singapore Options Course Singapore Options Trading Course Indonesia Options Course Seminar Jakarta Options Course Seminar Malaysia Options Course Seminar Options Spread Options Trading Options Trading Spread Futures Options Trading QQQQ Options Trading DIA Options Trading SPY Options Trading DIA Options Trading Non Directional Trading Ebook Options Trading Ebook Trade Like a Bookie Bookie Trading Strategy Futures Options Trading Articles. Non Directional Trading Non Directional Trading. Home Options Homestudy Course A Winning Trading System Handbook On Options Trading Free Inside Day Video About Us Contact **Home** Uncategorized. BLOG Options Homestudy Course A Directional Trading *Non* Options Trading Options Trading **Course** Options Trading Strategy. Dave Foo Handbook on Options Trading Non Directional Download Non Directional Options Trading Options Trading Course Options Trading System Options Trading Strategy Options Trading Method Options Trading EBook **Home** Selling Study Options Selling System Options Selling Course Options Selling Method Spread Trading Course **Directional** Trading Method Spread Trading System Singapore Options Seminar Singapore Options **Study** Singapore Options Trading Course Indonesia Options Download Seminar Jakarta Options Course Seminar Malaysia Trading Course **Options** Options Spread *Non* Trading Options Trading Spread Futures Options Trading QQQQ Options Trading DIA Options Trading SPY Options Trading DIA Options Trading Non Directional Trading Ebook Options Trading Ebook Trade Like a Bookie Bookie Trading Strategy Futures Options Trading Articles. CopyrightNon Directional Options Trading. Fearless, Confident Options Trading During Black Swan Events

However, it is not possible to come up with an example for each cell of these matrices because it is not possible to propose a non-directional and causal hypothesis.

This is why, for example, we can be more confident of research results that are consistent with a causal-directional hypothesis, than is the case of findings that are consistent with a non-directional hypothesis.

This lesson describes some refinements to the hypothesis testing approach that was introduced in the previous lesson. The truth of the matter is that the previous lesson was somewhat oversimplified in order to focus on the concept and general steps in the hypothesis testing procedure. With that background, we can now get into some of the finer points of hypothesis testing.

89%

of clients claim significantly improved grades thanks to our work.

98%

of students agree they have more time for other things thanks to us.

Clients Speak

“I didn’t expect I’d be thanking you for actually
improving my own writing, but I am. You’re like a second professor!”