# Get help with comparing two groups Recent questions in Comparing two groups
Comparing two groups
ANSWERED ### Water flows through a water hose at a rate of $$\displaystyle{Q}_{{{1}}}={680}{c}\frac{{m}^{{{3}}}}{{s}}$$, the diameter of the hose is $$\displaystyle{d}_{{{1}}}={2.2}{c}{m}$$. A nozzle is attached to the water hose. The water leaves the nozzle at a velocity of $$\displaystyle{v}_{{{2}}}={9.2}\frac{{m}}{{s}}$$. a) Enter an expression for the cross-sectional area of the hose, $$\displaystyle{A}_{{{1}}}$$, in terms of its diameter, $$\displaystyle{d}_{{{1}}}$$ b) Calculate the numerical value of $$\displaystyle{A}_{{{1}}},$$ in square centimeters. c) Enter an expression for the speed of the water in the hose, $$\displaystyle{v}_{{{1}}}$$, in terms of the volume floe rate $$\displaystyle{Q}_{{{1}}}$$ and cross-sectional area $$\displaystyle{A}_{{{1}}}$$ d) Calculate the speed of the water in the hose, $$\displaystyle{v}_{{{1}}}$$ in meters per second. e) Enter an expression for the cross-sectional area of the nozzle, $$\displaystyle{A}_{{{2}}}$$, in terms of $$\displaystyle{v}_{{{1}}},{v}_{{{2}}}$$ and $$\displaystyle{A}_{{{1}}}$$ f) Calculate the cross-sectional area of the nozzle, $$\displaystyle{A}_{{{2}}}$$ in square centimeters.

Comparing two groups
ANSWERED ### Water flows through a water hose at a rate of $$Q_{1}=680cm^{3}/s$$, the diameter of the hose is $$d_{1}=2.2cm$$. A nozzle is attached to the water hose. The water leaves the nozzle at a velocity of $$v_{2}=9.2m/s$$. a) Enter an expression for the cross-sectional area of the hose, $$A_{1}$$, in terms of its diameter, $$d_{1}$$ b) Calculate the numerical value of $$A_{1},$$ in square centimeters. c) Enter an expression for the speed of the water in the hose, $$v_{1}$$, in terms of the volume floe rate $$Q_{1}$$ and cross-sectional area $$A_{1}$$ d) Calculate the speed of the water in the hose, $$v_{1}$$ in meters per second. e) Enter an expression for the cross-sectional area of the nozzle, $$A_{2}$$, in terms of $$v_{1},v_{2}$$ and $$A_{1}$$ f) Calculate the cross-sectional area of the nozzle, $$A_{2}$$ in square centimeters.

Comparing two groups
ANSWERED ### The mean + 1 sd of In [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is $$6.56 + 0.64.$$ Similarly, the mean + 1 sd of In [calcium intake (mg)] among 40 females, 12 to 14 years of age, above the poverty level is $$6.80 + 0.76.$$ 8.2 Test for a significant difference between the variances of the two groups. 8.3 What is the appropriate procedure to test for a signifi- cant difference in means between the two groups? 8.4 Implement the procedure in Problem 8.3 using the critical-value method. 8.5 What is the p-value corresponding to your answer to Problem 8.4? 8.6 Compute a $$95\%$$ Cl for the difference in means between the two groups.

Comparing two groups
ANSWERED ### Decide equation using only factors to solve this problem $$12x^{2}\ +\ 5x\ -\ 2 = 0$$

Comparing two groups
ANSWERED ### Describe a possible application of hypothesis testing to a business setting. The application you describe need not be a real one (one that has actually occurred), it can be an application that you invent. You should describe a) what the business setting is b) what data you would use c) what null hypothesis you would test and what the alternative hypothesis is. d) what type of test you would use e) You should explain what level of significance you would use and why. f) You should explain how to interpret the outcome of the test: what does it tell you if you could reject or could not reject the null hypothesis? g) Finally, you should explain the possible advantages of using hypothesis testing in this application and its possible downsides dangers (when how using a hypothesis test could lead to mistaken inferences or erroneous decisions).

Comparing two groups
ANSWERED ### Population The resident population P (in millions) of the United States from 2000 through 2013 can be modeled by $$P = -0.00232t^{3} + 0.0151y^{2} + 2.83t + 281.8, 0 \leq t \leq 13,$$ where $$t = 0$$ corresponds to 2000. (Source: U.S. Census Bureau) Make a conjecture about the maximum and minimum populations of the United States from 2000 to 2013. Analytically find the maximum and minimum populations over the interval. The brief paragrah while comparing a conjecture with the minimum population was 281.8 million in 2000 and the maximum population was 316.1 million in 2013. We need to calculate: The absolute extrema of the popullation $$P = -0.00232t^{3} + 0.0151y^{2} + 2.83t + 281.8, 0 \leq t \leq 13$$ over the closed interval [0, 13].

Comparing two groups
ANSWERED ### Makes inferences about populations using data drawn from the population. Instead of using the entire population to gather the data, the statistician will collect a sample or samples from the millions of residents and make inferences about the entire population using the sample. histogram population mean descriptive statistics inferential statistics

Comparing two groups
ANSWERED ### Determine whether the situation involves comparing proportions for two groups or comparing two proportions from a single group. Then state whether the parameter of interest is in population proportions. For a population of all LCCC students, we would like to compare the proportion of students who use a Windows-based PC to the proportion who use a Mac. This situation involves ? and the parameter of interest is ? For a population of all registered voters in the United States, we would like to compare the males who voted in the last election to the proportion of females who voted in the last election. This situation involves ? and the parameter of interest is ?

Comparing two groups
ANSWERED ### Give a full answer to given question 1) An independent-measures study uses ? 2) An independent-measures study uses two samples, each with $$n = 13$$, to compare two treatment conditions. What is the df value for the t statistic for this study?

Comparing two groups
ANSWERED ### A new vaccine was tested to see if it could prevent the ear infections that many infants suffer from. Babies about a year old were randomly divided into two groups. One group received vaccinations, and the other did not. The following year, only 328 of 2460 vaccinated children had ear infections, compared to 508 of 2453 unvaccinated children. Complete parts a) through c) below. a) Are the conditions for inference satisfied? A. Yes. The data were generated by a randomized experiment, less than 10% of the population was sampled, the groups were independent, and there were more than 10 successes and failures in each group. B. No. It was not a random sample. C. No. The groups were not independent. D. No. More than 10% of the population was sampled.

Comparing two groups
ANSWERED ### In a one-way ANOVA, what does it mean to reject the statement in the null hypothesis if three treatment groups are being compared?

Comparing two groups
ANSWERED ### In how many ways can 7 graduate students be assigned to 1 triple and 2 double hotel rooms during a conference

Comparing two groups
ANSWERED ### Iron is very important for babies' growth. A common belief is that breastfeeding will help the baby to get more iron than formula feeding. To justify the belief, a study followed 2 groups of babies from born to 6 months. With one group babies are breast fed, and the other group are formula fed without iron supplements. Data below shows iron levels of those two groups of babies. $$\begin{array}{|c|c|} \hline Group & Sample\ size & mean & Standard\ deviation \\ \hline Breast-fed & 23 & 13.3 & 1.7 \\ \hline Formula-fed & 23 & 12.4 & 1.8 \\ \hline DIFF = Breast-Formula & 23 & 0.9 & 1.4 \\ \hline \end{array}$$ (1) There are two groups we need to compare for the study: Breast-Fed and Formula- Fed. Are those two groups dependent or independent? Based on your answer, what inference procedure should we apply for this research? (2) Please perform the inference you decided in (1), and make sure to follow the 5-step procedure for any hypothesis test. (3) Based on your conclusion in (2), what kind of error could you make? Explain the type of error using the context words for this research

Comparing two groups
ANSWERED ### Give a full and correct answer Why is it important that a sample be random and representative when conducting hypothesis testing? Representative Sample vs. Random Sample: An Overview Economists and researchers seek to reduce sampling bias to near negligible levels when employing statistical analysis. Three basic characteristics in a sample reduce the chances of sampling bias and allow economists to make more confident inferences about a general population from the results obtained from the sample analysis or study: * Such samples must be representative of the chosen population studied. * They must be randomly chosen, meaning that each member of the larger population has an equal chance of being chosen. * They must be large enough so as not to skew the results. The optimal size of the sample group depends on the precise degree of confidence required for making an inference. Representative sampling and random sampling are two techniques used to help ensure data is free of bias. These sampling techniques are not mutually exclusive and, in fact, they are often used in tandem to reduce the degree of sampling error in an analysis and allow for greater confidence in making statistical inferences from the sample in regard to the larger group. Representative Sample A representative sample is a group or set chosen from a larger statistical population or group of factors or instances that adequately replicates the larger group according to whatever characteristic or quality is under study. A representative sample parallels key variables and characteristics of the large society under examination. Some examples include sex, age, education level, socioeconomic status (SES), or marital status. A larger sample size reduced sampling error and increases the likelihood that the sample accurately reflects the target population. Random Sample A random sample is a group or set chosen from a larger population or group of factors of instances in a random manner that allows for each member of the larger group to have an equal chance of being chosen. A random sample is meant to be an unbiased representation of the larger population. It is considered a fair way to select a sample from a larger population since every member of the population has an equal chance of getting selected. Special Considerations: People collecting samples need to ensure that bias is minimized. Representative sampling is one of the key methods of achieving this because such samples replicate as closely as possible elements of the larger population under study. This alone, however, is not enough to make the sampling bias negligible. Combining the random sampling technique with the representative sampling method reduces bias further because no specific member of the representative population has a greater chance of selection into the sample than any other. Summarize this article in 250 words.

Comparing two groups
ANSWERED ### Describe why comparing the factor variance and error variance with an ANOVA analysis will indicate if groups come from the same or different populations.

Comparing two groups
ANSWERED ### For the following exercises, use this scenario: The population of a city has risen and fallen over a 20-year interval. Its population maybe modeled by the following function: $$y = 12.000 + 8.000 \sin(0.628x)$$, where the domain is the years since 1980 and the range is the population of the city. Graph the function on the domain of [0,40]

Comparing two groups
ANSWERED ### In a chi-square test for independence, the null hypotesis is that ?

Comparing two groups
ANSWERED ### Solve given question :Situation comparing two proportions is described below. Determine whether the situation involves comparing proportions for two groups or comparing two proportions from the same group. Compare the proportion of teachers who use internet to send email for professional activities and for student activities.

Comparing two groups
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