Week 9_Frequency Distribution, Cross Tabulations & Hypothesis Testing Flashcards
what is valid percentage for frenquency of distribution?
exclude missing response
Which mesurement is most commn used of central tendency?
Mean value
The mode value is good for which usage?
The mode is a good measure of location when the variable is inherently categorical or has otherwise been grouped into categories.
What skewness can do?
the tendency of the deviations from the mean being larger in one direction than in the other. It can be thought of as the tendency for one tail of the distribution to be heavier than the other.
What is Kurtosis
a measure of the relative peak or flatness of the curve defined by the frequency distribution.
Features of Kurtosis of
– The kurtosis of a normal distribution is zero.
– If the kurtosis is positive, then the distribution is more
peaked than a normal distribution.
– A negative value means that the distribution is flatter than a normal distribution.
What is null hypothesis
=no difference or no effect. if no reject, no change
What is alternative hypothesis?
some difference or effect is expected. Accepting the alternative hypothesis will lead to changes in opinions or actions.
What is cross-tabulation analysis?
wo categorical variables are arranged in a cross-tabulation table (a table in which data are compared using a row-and-column format).
The Cross-tabulation table only depicts the two variables simultaneously; it is NOT a statistical test.
True
What is Chi-square?
examination of frequencies for two categorical variables in a cross-tabulation table to determine whether the variables have a significant relationship.
Chi-square (𝜒2) analysis is a statistical test
True
How to calculate Chi-square?
lump sum of (observe frequency - expected frequency)/expected frequency
How to calculate expected frequency?
Cell column total*Cell row total/grand total
How to calculate degree of freedom in Chi-square?
(Number of rows - 1)*(Number of column - 1)
The relationship between critical table value and chi-square value
if chi-square value is bigger than critical table value, which means null-hypothesis (no significant relationship between two variables) is rejected and there is a significant relationship between two variables.
How to get critical table value?
Base on degree of freedom, check chi-squaire distribution and get the table value.
Chi-square value > critical table value, then null-hypothesis is not support, then alternative hypothesis is accepted.
True
What is meaning of reject null-hypothesis?
Accept alternative hypothesis and show changes and difference.
Two classification of hypothesis tests
Test of association and test of difference
How to formulate hypothesis?
In marketing research, null hypothesis is formulated in such a way that its rejection leads to the acceptance of the desired conclusion
For example, if you want to numbers of online shopping bigger than 40%, then you set null hypothesis H0 <40%， Alternative hypothesis H1 >40%
How to express hypothesis if research involve proportion?
Two-tailed test required and hypothesis will be expressed as H0=40% H1 not = 40%
Different between t test and z test
sample numbers
What is type one error?
when the sample results lead to the rejection of the null hypothesis when it is in fact true.
What is type two error?
when, based on the sample results, the null hypothesis is not rejected when it is in fact false.
What is level of significance?
Depends on different situation, choose type one error or type to error.
What value for probability of type one error?
0.05
What value for probability of type two error?
depends on the actual value of the population parameter (mean or proportion).
What is power of test?
probability (1 − β) of rejecting
the null hypothesis when it is false and should be rejected
The probability associated with the calculated or observed value of the test statistic is 0.0301 (this is the probability of getting a p value of 0.567 when π = 0.40).
This is less than the level of significance of 0.05. Hence, the null hypothesis is rejected.
True
- Parametric tests assume that the variables of interest are measured on at least an interval scale.
- Nonparametric tests assume that the variables are measured on a nominal or ordinal scale.
True
Parametric test
The variable is normally distributed and the mean is known (or assumed to be known) and the population variance is estimated from the sample.
Calculated value greater than table value, null hypothesis is rejected.
true
The relationship between K value and decision of null hypothesis rejection.
The larger K is, the more confidence we have that H0 is false
K=critical table value/n^2
If p value <0.05 (95% confidence level) there is significant difference
True
