Hypothesis testing Definition and 86 Threads

Homework Statement Hi, this is a stats question, hope I'm asking it in the right place. I am estimating an animal populations health based on it's weight to length ratio, I have a population ratio (10grams/cm) from 5 years ago and a sample estimate made from recently gathered data. I am...

I have a question about the equations used for hypothesis testing. They all look like this one here: H0: μ = μ0 H1: μ > μ0 For various situations.. sigma know, sigma unknown etc. So H0 is the first claim and H1 is the second claim. But this means the second claim is > than the first...

Hello folks. This was in my exam and I wasn't sure how to solve it. Homework Statement A sample of 67 respondents was taken collectively by a population of 6,456 units. The number of those who said they were available to implement a development program were 35. To implement the program...

Ok someone tell me the official explanation of why alpha cannot be zero in hypothesis testing.

hi guys, I'm trying to understand how the critical value of Q-statistics is calculated in multivariate ljung-box test. or even more simply, in the univariate ljung-box test. initially i used MATLAB for hypothesis testing, MATLAB as an output furnishes the critical values, but the modules in...

Suppose X is normal mean \mu unknown and standard deviation σ = 1. (a) You are to show that the uniformly most powerful test for testing test of size α based on a sample of size n for testing H0 :\mu  ≤ \mu0 verses H1\mu :  ≥ \mu0 is of the form R = {\Sigmaxj ≥ c} where c = z\sqrt{n} +...

Homework Statement During a water shortage in Florida, restaurants were asked not to serve water with meals unless requested to do so by customers. In the initial 3-month period, 45% of the customers served at a particular restaurant requested water with their meal. Recently, the restaurant...

I am not sure whether this falls in this section or the other. But as the calculation of likelihood usually involves calculus, posting it here. Homework Statement The Big Boss at Amazoogle.com says that based on long experience, the best model for errors in software is that experienced...

How is hypothesis testing performed for multivariate data? Say for simplicity we have two iid draws from a binomial distribution Bin(10,q) with X1=7, X2=8. Under the null hypothesis H0:q=1/2, the individual p-values (as one-tail probabilities) are approximately 0.172 and 0.055 respectively...

Homework Statement A source is supposed to emit photons with spin +/-1 independently at equal rate. a) after measuring 4 photons, all have spin +1; b) after measuring 100 photons, 60 have spin +1. at which confidence level can the hypothesis be rejected. Calculate for each of the...

Homework Statement A cola company's long-term market share is estimated to be 45%. After an extensive advertising campaign, 68 out of 150 customers surveyed claimed to have purchased this company's cola recently. Was the advertising campaign a success? justify your assessment Homework...

Homework Statement Let X have a binomial distribution with the number of trails n = 10 and with p either 0.25 or 0.5. The simple null hypothesis p = 0.5 is rejected and the alternate hypothesis p = 0.25 is accepted if the observed value of X1, a random sample of size 1, is less than or equal...

Homework Statement Let X have a binomial distribution with the number of trails n = 10 and with p either 0.25 or 0.5. The simple null hypothesis p = 0.5 is rejected and the alternate hypothesis p = 0.25 is accepted if the observed value of X1, a random sample of size 1, is less than or equal...

Homework Statement A drug company markets a medication that cures about 60% of cases with depression. A CB program is thought to be more effective. It was delivered to 15 depressed people. Determine the minimum number of cured people required to support the claim that the CB program is more...

Homework Statement Karen asks John to guess the date of her birth, not including the year (i.e. the day and month she was born; discount leap years). If John guessed correctly on his first try, would you believe his claim that he made a lucky guess or would you be suspicious that he already...

Hi, I'm interested in this question primarily in how it relates to what is usually called classic or frequentist statistics (p-values, etc). I'm fully aware of how stepwise and other automated techniques can negatively impact analyses and render inference based upon parameter estimates...

Homework Statement A hire-car firm is considering a special bumper bar designed to lower the cost of car repairs following minor accidents. This bumper bar is more expensive than the conventional one. It will only be introduced permanently if any reduction in the cost of repairs is judged to...

Homework Statement A random sample of 30 rats has 18 females and 12 males. If last year's proportion of females treated was 0.65, do the above data confirm that this year the proportion of females is different than last year? Homework Equations p = treated / total If using standard...

Hi, I have a large data set with with less than 10% missing values (missing response, but all predictor variables present). It is a near certainty that these values are not missing at random, dependent upon the missing value. The response is survival time of a land parcel with 'death' being...

If \sigma = 10 km/h and \mu = 74 km/t, find the probability that we when measuring the speed of 12 random cars can conclude that the expected speed of the cars is less than 77 km/h. Use \alpha=0.05 level of significance. z = \frac{\bar{x}-\mu_0}{\sigma / \sqrt{n}} =...

Homework Statement 1a) The strength of concrete depends to some extent on the method used for drying it. Two different drying methods were tested independently on specimens. The strength using each of the methods follow a normal distribution with mean μ_x and μ_y respectively and the same...

Homework Statement http://www.geocities.com/asdfasdf23135/stat14.JPG Homework Equations Statistics: power function The Attempt at a Solution a) Test statistic: Z = (X bar - 13) / (4/sqrt n) Let μ = μ_a > 13 be a particular value in H_a Power(μ_a) = 1- beta(μ_a) = P(reject Ho |...

What is the difference between NOT being able to reject the hypothesis that a particular parameter is zero and being able to conclude that it is within some acceptable distance from zero ("practical equivalence")? I guess this is more of a logic question, but I'm still having trouble...

Homework Statement I have used OLS and found that: b0 = 6,85 b1 = 3,88 with se= 0,1121 n = 20 Person x claims that b1 = 5 Choose an alternative hypothesis. Does your estimated relationship support this claim? Use a 5 % significance level The Attempt at a Solution H0 = b1 =...

Hi guys. Im new at this site so please be nice to me =P. I've been working on some practice papers for my upcoming end of semester exams. Cant get these two questions out ><. Any help is greatly appreciated Thanks in advance jenny xoxo 1. A sample of 28 students measured their...

Homework Statement Having trouble understanding the question, which is... voltage specified to be 130 Sample of 20 readings gives sample mean of 128.25 Also given s.d.=3. "It is important that the voltage not be allowed to drop below 128 volts. What is the probability of rejecting mean...

Homework Statement A machine produces metal rods used in an automobile suspension system. A random sample of 12 rods is selected and the diameter is measred.The sample mean is 8.28. and the significance level is 0.05. Is there strong evidence to indicate that mean rod diameter is not 8.20 mm...

Homework Statement I have two variables (both nominal) union membership 1/0 and race 1/0 and I have to find if there is a relationship between them. The task is formulated like so: "Is there a relationship between union membership and race (black versus non-black)?" I know I have to state...

I really don't understand hypothesis testing. How do I recognize which one is Ho and Ha in a problem? Is there a particular trick to facilitate my lfie?

Need to know the test that will be performed on the following question: The data comprises hours devoted to patient care per week for practitioners in conventional and alternative medical practices. Question: Can we infer that the mean amount of time devoted to patient care per week by...

First and foremost, I am terrible in Stats so bear w/ me on this one. This is my question, if anyone has an idea on how to figure out this problem that would be great! Here it is: Suppose you flip a coin 100 times and you want to test the hypothesis that the coin is fair, making sure there is...

I need some help with a problem. Let me first post the results. 289 (10 lottery ball random draws) = 4.66 ave...5.50 mean 67 (9 lottery ball random draws) = 3.30 ave...5.00 mean 49 (8 lottery ball random draws) = 4.08 ave ...4.50 mean 37 (7 lottery ball random draws) = 3.00 ave...4.00 mean...

I am having trouble understanding the concept of the power of the test. Here is a sample question with solution: A company wants to test if average weekly demand is more than 2000 lbs. Test is to be carried out at 5% level of significance, and an estimate of the population variance is...

Hypothesis testing with normal distribution... I've been learning about Hypothesis testing with normal distribution, but I don't understand the need for the significance level. By this I mean that i understand that according to the Central Limit Theorem a distribution of the means will be a...

i'm getting my concepts very confused now... so the formula for the normal distri is (y - u)/(sigma)/((sqroot(n)). so if I want to test y, I set that formula = to alpha(where alpha is the confidence level). that is if it is one sided. if it is 2 sided, do I still set it to alpha, or...

Using a .05 level of sign, test the hyp that the probability of the NCAA champion being from the big east is 20% The actual ratio is 3/63 Where should I start? thanks nautica