Making conclusions about the difference of means Video transcript - [Instructor] "Market researchers conducted a study "comparing the salaries of managers "at a large nationwide retail store. So, pause this video and try to figure this out on your own. So first, let's think about the difference between a paired T test and a two-sample T test.
A variable is a characteristic or factor that has values that vary. Thus, a variable has at least two different categories or values.
Examples of category systems include: At a minimum, category systems should be exhaustive cover all cases. Each case must be able to fit into a category.
Sometimes that means we must construct an all-inclusive "other" category. Categories of a variable should also be mutually exclusive each case fits into one and only ONE category.
Possibilities IF the data allow include a normal "bell-shaped" or Gaussian distribution or an equiprobable distribution in which each category has the same number of cases. Researchers should try to gather data as completely as possible for example, get education in number of years rather than degree level because one can collapse or move around categories later on with computer programs.
Avoid "open-ended" categories that do not have fixed end points when possible e.
|Testing the difference between two means||Contact Us Null and Alternative Hypothesis Generally to understand some characteristic of the general population we take a random sample and study the corresponding property of the sample.|
|Purchase Solution||The null hypothesis itself does not involve the data. It is a statement about a parameter a numerical characteristic of the population.|
|Examples of the Null Hypothesis||Based on whether it is true or not determines whether we accept or reject the hypothesis.|
|Hypothesis Testing - Analysis of Variance (ANOVA)||Means are not all equal.|
Make questions and responses explicit enough that respondents or interviewers do not need to guess about the answer. Nominal, ordinal and interval-ratio variables are different types of category systems.
These form a cumulative and hierarchical set of data properties, so that nominal properties are true for ordinal and interval data. And ordinal properties are also true for interval data. The reverse does NOT hold. Thus, you can sort all cases into mutually exclusive, exhaustive categories.
Examples of nominal variables include: Zodiac sign Birth country and Religious affiliation or denomination Nominal variables are also sometimes called categorical variables or qualitative variables. The categories are not only not numbers, they do not have any inherent order.
South Koreans or Turks? Country of origin is NOT a number or even a "relative judgment". If you suspect that ranking the categories NOTE: NOT the cases within the categories would start a war, you probably have nominal variables. You can only do very basic statistics or presentations with nominal data, such as: Of course, many nominal variables are very important, especially as explanatory variables.
This means the scores must be rank-ordered from highest to lowest or vice versa first, before any ordinal statistics can be used. Like runners in a race, we can rank scores--and the categories themselves--from first to last, most to least, or highest to lowest.
In rank-ordered cases, we can literally rank order the finishers in a race or the students by their grade point average first in class, second in class, and so on down to last in class.
Notice that the intervals between cases probably are not the same or equal. The class valedictorian may have a straight-A or 4.
The fastest runner might run a mile in 5 minutes, the second fastest in 5 minutes 10 seconds 10 seconds slowerthe third runner in 6 minutes 50 seconds slower still.
We can also rank-order the categories of a variable in ordinal data. One example is a Likert scale. Respondents are given a statement, such as "I like the Big Bang Theory" then asked if they: We can surmise that someone who "strongly agrees" supports that statement more intensely than someone who "agrees"--but we don't know how much more intensely.
Most Agree-Disagree Likert attitude scales are ordinal data. Someone who smokes cigarettes "at all" and answers "yes" smokes more than someone who smokes zero cigarettes and answers "no"even if it is only 1 cigarette more. In addition, with ordinal data, you can do percentiles, quartiles, and medians the category that includes the 50th percentile.
Most statistical processing computer programs, such as SPSS, assign numbers to all categories as a default, even to non numeric nominal and ordinal variables. This is for data processing ease and does not give you any clues as to the type of data you have.
Number of books is a ratio variable.The null hypothesis, H 0 is the commonly accepted fact; it is the opposite of the alternate hypothesis. Researchers work to reject, nullify or disprove the null hypothesis.
Researchers work to reject, nullify or disprove the null hypothesis. The null hypothesis (H 0) is a hypothesis which the researcher tries to disprove, reject or nullify.
The 'null' often refers to the common view of something, while the alternative hypothesis is what the researcher really thinks is the cause of a phenomenon. An experiment conclusion always refers to the null, rejecting or accepting H 0 rather than .
Observation: Suppose we perform a statistical test of the null hypothesis with α and obtain a p-value of p, thereby rejecting the null hypothesis.
This does not mean that there is a 4% probability of the null hypothesis being true, i.e. P (H 0) parameters. Hypothesis testing implies making a decision, on the basis of sample data, on whether to reject that certain restrictions are satisfied by the basic assumed model. The restrictions we are going to test are known as the null hypothesis, denoted by H0.
Thus, null . The null hypothesis sometimes is called the "no difference" hypothesis. The null hypothesis is good for experimentation because it's simple to disprove.
If you disprove a null hypothesis, that is evidence for a relationship between the variables you are examining. Write the null and alternative hypothesis symbolically and identify which hypothesis is the claim.
Is the test two-tailed, left-tailed, or right-tailed? Explain.