A

**case**-**cohort study**is similar to a nested**case**-control**study**in that the**cases**and non-**cases**are within a parent**cohort**;**cases**and non-**cases**are identified at time t_{1}, after baseline. Non-**cases**are randomly selected from the parent**cohort**, forming a subcohort.Similarly, what is an example of a case control study?

A

**study**that compares patients who have a disease or outcome of interest (**cases**) with patients who do not have the disease or outcome (**controls**), and looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the risk factor and the1

## What are matched pairs stats?

A

**matched pairs**design is a special case of a randomized block design. It can be used when the experiment has only two treatment conditions; and subjects can be grouped into**pairs**, based on some blocking variable. Then, within each**pair**, subjects are randomly assigned to different treatments.2

## What is a matched group?

One important type of experimental design is a

**matched**-subjects design, also called a**matched**-**group**design, which is when subjects are**matched**on some variable that might be affecting the dependent variable and then split into two or more**groups**.3

## Are matched pairs independent?

The opposite of a

**matched**sample is an**independent**sample, which deals with unrelated groups. While**matched pairs**are chosen deliberately,**independent**samples are usually chosen randomly (through simple random sampling or a similar technique).4

## What is a matched pair t test?

The

**matched**-**pair t**-**test**(or**paired t**-**test**or**paired**samples**t**-**test**or dependent**t**-**test**) is used when the data from the two groups can be presented in**pairs**, for example where the same people are being measured in before-and-after comparison or when the group is given two different**tests**at different times (eg.5

## What is an Anova test used for?

Analysis of Variance (

**ANOVA**) is a statistical method used to**test**differences between two or more means. It may seem odd that the technique is called "Analysis of Variance" rather than "Analysis of Means." As you will see, the name is appropriate because inferences about means are made by analyzing variance.6

## What is a paired t test used for?

The

**paired**sample**t**-**test**, sometimes called the dependent sample**t**-**test**, is a statistical procedure used to determine whether the mean difference between two sets of observations is zero. In a**paired**sample**t**-**test**, each subject or entity is measured twice, resulting in pairs of observations.7

## Why would you use a paired t test?

A

**paired t**-**test**is used to compare two population means where you have two samples in which observations in one sample can be**paired**with observations in the other sample. To**test**the null hypothesis that the true mean difference is zero, the procedure is as follows: 1.8

## What is the difference between paired and unpaired t test?

Both

**t**.**tests test**for the difference between two sample means.**Unpaired t**-**test**(aka Student's**test**) compares two different subjects. The**paired t**-**test**reduces intersubject variability (because it makes comparisons between the same subject), and thus is theoretically more powerful than the**unpaired t**-**test**.9

## What is paired and unpaired t test?

**Unpaired**(Two Sample)

**t Test**. The

**unpaired t**method

**tests**the null hypothesis that the population means related to two independent, random samples from an approximately normal distribution are equal (Altman, 1991; Armitage and Berry, 1994).

10

## What is the difference between paired and unpaired data?

Scientific experiments often consist of comparing two or more sets of

**data**. This**data**is described as**unpaired**or independent when the sets of**data**arise from separate individuals or**paired**when it arises from the same individual at different points in time.11

## What is the difference between an Anova and a t test?

The significant

**differences between T**-**test and ANOVA**are discussed in detail**in the**following points: A hypothesis**test**that is used to compare the means of two populations is called**t**-**test**. A statistical technique that is used to compare the means of more than two populations is known as Analysis of Variance or**ANOVA**.12

## What is a paired analysis?

In statistics, a

**paired**difference test is a type of location test that is used when comparing two sets of measurements to assess whether their population means differ. The most familiar example of a**paired**difference test occurs when subjects are measured before and after a treatment.13

## What is the paired comparison method?

Definition:

**Paired Comparison Method**.**Paired comparison**involves**pairwise comparison**– i.e.,**comparing**entities in pairs to judge which is preferable or has a certain level of some property. LL Thurstone first established the scientific**approach**to using this**approach**for measurement.14

## What kind of test to use?

Types of Statistical Tests

Type of Test | Use |
---|---|

Paired T-test | Tests for the difference between two related variables |

Independent T-test | Tests for the difference between two independent variables |

ANOVA | Tests the difference between group means after any other variance in the outcome variable is accounted for |

15

## What does the chi square test tell you?

The Chi-square test is intended to test how likely it is that an

**observed**distribution is due to chance. It is also called a "goodness of fit" statistic, because it measures how well the**observed**distribution of data**fits**with the distribution that is expected if the variables are independent.16

## Which SPSS test to use?

Choosing the Correct Statistical Test in SAS, Stata, SPSS and R

Number of Dependent Variables | Nature of Independent Variables | Test(s) |
---|---|---|

2+ | 1 IV with 2 or more levels (independent groups) | one-way MANOVA |

2+ | multivariate multiple linear regression | |

0 | factor analysis | |

2 sets of 2+ | 0 | canonical correlation |

17

## What is the best statistical test to compare two groups?

Choosing a statistical test

Type of Data | ||
---|---|---|

Compare one group to a hypothetical value | One-sample ttest | Wilcoxon test |

Compare two unpaired groups | Unpaired t test | Mann-Whitney test |

Compare two paired groups | Paired t test | Wilcoxon test |

Compare three or more unmatched groups | One-way ANOVA | Kruskal-Wallis test |

18

## What is an example of ordinal data?

**Ordinal data**is a categorical,

**statistical data**type where the variables have natural, ordered categories and the distances between the categories is not known. These

**data**exist on an

**ordinal**scale, one of four levels of measurement described by S. S. Stevens in 1946.

19

## What is an example of an ordinal variable?

An

**ordinal variable**is a categorical**variable**for which the possible values are ordered.**Ordinal variables**can be considered “in between” categorical and quantitative**variables**. Example: Educational level might be categorized as.20

## What is a ratio variable?

**Ratio variables**are interval

**variables**, but with the added condition that 0 (zero) of the measurement indicates that there is none of that variable. So, temperature measured in degrees Celsius or Fahrenheit is not a

**ratio**variable because 0C does not mean there is no temperature.